Method and system for additive manufacturing using high energy source and hot-wire

ABSTRACT

A method and system to manufacture workpieces employing a high intensity energy source to create a puddle and at least one resistively heated wire which is heated to at or near its melting temperature and deposited into the puddle as droplets.

PRIORITY

The present application is a continuation in part of, and claimspriority to, U.S. patent application Ser. No. 14/163,367 filed on Jan.24, 2014, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Certain embodiments relate to additive manufacturing applications. Moreparticularly, certain embodiments relate to a system and method to use acombination filler wire feed and energy source system for additivemanufacturing applications.

BACKGROUND

The use of additive manufacturing has grown recently using variousmethods. However, known methods have various disadvantages. For example,some processes use metal powders which are generally slow and can resultin a fair amount of waste of the powders. Other methods, which use arcbased systems, are also slow and do not permit for the manufacture ofhighly precise articles of manufacture. Therefore, there is a need foradditive manufacturing processes and systems which can operate a highspeeds, with a high level of precision.

Further limitations and disadvantages of conventional, traditional, andproposed approaches will become apparent to one of skill in the art,through comparison of such approaches with embodiments of the presentinvention as set forth in the remainder of the present application withreference to the drawings.

SUMMARY

Embodiments of the present invention comprise a system and method foradditive manufacturing where a high energy device irradiates a surfaceof a work piece with a high energy discharge to create a molten puddleon a surface of the work piece. A wire feeding device feeds a wire tothe puddle, and a power supply supplies a heating signal to the wirewhere the heating signal comprises a plurality of current pulses andwhere each of the current pulses creates a molten droplet on a distalend of the wire which is deposited into the puddle. Each of the currentpulses reaches a peak current level after the wire feeder causes thedistal end of the wire to contact said puddle and the heating signal hasno current in between the plurality of the current pulses. The wirefeeder controls the movement of the wire such that the distal end of thewire is not in contact with the puddle between subsequent peak currentlevels of the current pulses, and the power supply controls the heatingcurrent such that no arc is created between the wire and the work pieceduring the current pulses.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the invention will be more apparent bydescribing in detail exemplary embodiments of the invention withreference to the accompanying drawings, in which:

FIG. 1 illustrates a schematic block diagram of an exemplary embodimentof an additive manufacturing system of the present invention;

FIGS. 2A to 2D illustrate a droplet deposition process in accordancewith an exemplary embodiment of the present invention;

FIG. 3 illustrates another view of a droplet deposition process inaccordance with an exemplary embodiment of the present invention;

FIGS. 4A to 4B illustrate representative current waveforms that can beused with embodiments of the present invention;

FIG. 5 illustrates a representative embodiment of a voltage and currentwaveform of the present invention;

FIGS. 6A and 6B illustrate utilization of a laser to aid in dropletdeposition;

FIG. 7 illustrates an exemplary embodiment of wire heating system inaccordance with an aspect of the present invention;

FIG. 8A illustrates an exemplary embodiment of a current waveform thatcan be used with the system of FIG. 7;

FIG. 8B illustrates an exemplary embodiment of waveforms for current,voltage, wire feed speed and laser power for an exemplary embodiment ofthe present invention;

FIG. 9 illustrates another exemplary embodiment of a wire heating systemof the present invention;

FIG. 10 illustrates a further exemplary embodiment of the presentinvention using multiple wires;

FIG. 11 illustrates another exemplary embodiment of a system of thepresent invention;

FIG. 12 illustrates a power supply system in accordance with anembodiment of the present invention;

FIG. 13 illustrates an embodiment of a system which uses multipleconsumables at one time;

FIG. 14 illustrates an another embodiment of the system in FIG. 13;

FIG. 15 illustrates a further exemplary embodiment of the system shownin FIG. 13;

FIG. 16 illustrates an exemplary embodiment of a non-bondingmanufacturing substrate;

FIG. 17A to 17C illustrate further exemplary embodiments of anon-bonding manufacturing substrate;

FIG. 18A illustrates an embodiment of a non-bonding substrate having acooling system;

FIG. 18B illustrates an exemplary embodiment of a manufacture trussstructure that can be used with embodiments of the present invention;

FIGS. 19A to 19C illustrate exemplary embodiments of braided additivemanufacturing consumables that can be used with systems describedherein;

FIGS. 20A to 20B illustrate an exemplary braided consumable that hasbeen deformed in accordance with embodiments of the present invention;

FIG. 20C illustrates an embodiment of a dual wire deposition contact tipassembly as described herein;

FIG. 20D illustrates a further exemplary embodiment of a dual wirecontact tip of the present invention;

FIGS. 21A and 21B illustrate an exemplary contact tip assembly of thepresent invention that can be used to deform consumables for deliveryduring a deposition process;

FIG. 22 illustrates another exemplary consumable of the presentinvention;

FIG. 23 illustrates a further exemplary embodiment of a consumable foradditive manufacturing as described herein; and

FIGS. 24A to 24D illustrates additional exemplary embodiments ofadditive manufacturing consumables that can be used with embodiments ofthe present invention.

DETAILED DESCRIPTION

Exemplary embodiments of the invention will now be described below byreference to the attached Figures. The described exemplary embodimentsare intended to assist the understanding of the invention, and are notintended to limit the scope of the invention in any way. Like referencenumerals refer to like elements throughout.

The term “additive manufacturing” is used herein in a broad manner andmay refer to any applications including building up, constructing, orcreating objects or components

FIG. 1 illustrates a functional schematic block diagram of an exemplaryembodiment of a combination filler wire feeder and energy source system100 for performing additive manufacturing. The system 100 includes alaser subsystem capable of focusing a laser beam 110 onto a workpiece115 to heat the workpiece 115. The laser subsystem is a high intensityenergy source. The laser subsystem can be any type of high energy lasersource, including but not limited to carbon dioxide, Nd:YAG, Yb-disk,YB-fiber, fiber delivered or direct diode laser systems. Otherembodiments of the system may include at least one of an electron beam,a plasma arc welding subsystem, a gas tungsten arc welding subsystem, agas metal arc welding subsystem, a flux cored arc welding subsystem, anda submerged arc welding subsystem serving as the high intensity energysource. The following specification will repeatedly refer to the lasersystem, beam and power supply, however, it should be understood thatthis reference is exemplary as any high intensity energy source may beused. For example, a high intensity energy source can provide at least500 W/cm². The laser subsystem includes a laser device 120 and a laserpower supply 130 operatively connected to each other. The laser powersupply 130 provides power to operate the laser device 120.

The system 100 also includes a hot filler wire feeder subsystem capableof providing at least one resistive filler wire 140 to make contact withthe workpiece 115 in the vicinity of the laser beam 110. Of course, itis understood that by reference to the workpiece 115 herein, the moltenpuddle is considered part of the workpiece 115, thus reference tocontact with the workpiece 115 includes contact with the puddle. Thewire feeder subsystem includes a filler wire feeder 150, a contact tube160, and a power supply 170. During operation, the filler wire 140 isresistance-heated by electrical current from the power supply 170 whichis operatively connected between the contact tube 160 and the workpiece115. In accordance with an embodiment of the present invention, thepower supply 170 is a pulsed direct current (DC) power supply, althoughalternating current (AC) or other types of power supplies are possibleas well. The wire 140 is fed from the filler wire feeder 150 through thecontact tube 160 toward the workpiece 115 and extends beyond the tube160. The extension portion of the wire 140 is resistance-heated suchthat the extension portion approaches or reaches the melting pointbefore contacting a puddle on the workpiece. The laser beam 110 servesto melt some of the base metal of the workpiece 115 to form a puddle andcan also be used to melt the wire 140 onto the workpiece 115. The powersupply 170 provides energy needed to resistance-melt the filler wire140. As will be explained further below, in some embodiments the powersupply 170 provides all of the energy needed while in other embodimentsthe laser or other high energy heat source can provide some of theenergy. The feeder subsystem may be capable of simultaneously providingone or more wires, in accordance with certain other embodiments of thepresent invention. This will be discussed more fully below.

The system 100 further includes a motion control subsystem capable ofmoving the laser beam 110 (energy source) and the resistive filler wire140 in a same direction 125 along the workpiece 115 (at least in arelative sense) such that the laser beam 110 and the resistive fillerwire 140 remain in a fixed relation to each other. According to variousembodiments, the relative motion between the workpiece 115 and thelaser/wire combination may be achieved by actually moving the workpiece115 or by moving the laser device 120 and the wire feeder subsystem. InFIG. 1, the motion control subsystem includes a motion controller 180operatively connected to a robot 190. The motion controller 180 controlsthe motion of the robot 190. The robot 190 is operatively connected(e.g., mechanically secured) to the workpiece 115 to move the workpiece115 in the direction 125 such that the laser beam 110 and the wire 140effectively travel along the workpiece 115. In accordance with analternative embodiment of the present invention, the laser device 110and the contact tube 160 may be integrated into a single head. The headmay be moved along the workpiece 115 via a motion control subsystemoperatively connected to the head.

In general, there are several methods that a high intensity energysource/wire may be moved relative to a workpiece. If the workpiece isround, for example, the high intensity energy source/wire may bestationary and the workpiece may be rotated under the high intensityenergy source/wire. Alternatively, a robot arm or linear tractor maymove parallel to the round workpiece and, as the workpiece is rotated,the high intensity energy source/wire may move continuously or indexonce per revolution to, for example, overlay the surface of the roundworkpiece. If the workpiece is flat or at least not round, the workpiecemay be moved under the high intensity energy source/wire as shown ifFIG. 1. However, a robot arm or linear tractor or even a beam-mountedcarriage may be used to move a high intensity energy source/wire headrelative to the workpiece.

The system 100 further includes a sensing and current control subsystem195 which is operatively connected to the workpiece 115 and the contacttube 160 (i.e., effectively connected to the output of the power supply170) and is capable of measuring a potential difference (i.e., a voltageV) between and a current (I) through the workpiece 115 and the wire 140.The sensing and current control subsystem 195 may further be capable ofcalculating a resistance value (R=V/I) and/or a power value (P=V*I) fromthe measured voltage and current. In general, when the wire 140 is incontact with the workpiece 115, the potential difference between thewire 140 and the workpiece 115 is zero volts or very nearly zero volts.As a result, the sensing and current control subsystem 195 is capable ofsensing when the resistive filler wire 140 is in contact with theworkpiece 115 and is operatively connected to the power supply 170 to befurther capable of controlling the flow of current through the resistivefiller wire 140 in response to the sensing, as is described in moredetail later herein. In accordance with another embodiment of thepresent invention, the sensing and current controller 195 may be anintegral part of the power supply 170.

In accordance with an embodiment of the present invention, the motioncontroller 180 may further be operatively connected to the laser powersupply 130 and/or the sensing and current controller 195. In thismanner, the motion controller 180 and the laser power supply 130 maycommunicate with each other such that the laser power supply 130 knowswhen the workpiece 115 is moving and such that the motion controller 180knows if the laser device 120 is active. Similarly, in this manner, themotion controller 180 and the sensing and current controller 195 maycommunicate with each other such that the sensing and current controller195 knows when the workpiece 115 is moving and such that the motioncontroller 180 knows if the filler wire feeder subsystem is active. Suchcommunications may be used to coordinate activities between the varioussubsystems of the system 100.

As is generally known, additive manufacturing is a process in which amaterial is deposited onto a workpiece so as to create desiredmanufactured product. In some applications the article of manufacturecan be quite complex. However, known methods and systems used foradditive manufacturing tend to be slow and have limited performance.Embodiments of the present invention address those areas by providing ahigh speed and highly accurate additive manufacturing method and system.

The system 100 depicted in FIG. 1 is such an exemplary system, where thewire 140 is repeatedly melted, in droplets, and deposited onto theworkpiece to create the desired shape. This process is exemplarydepicted in FIGS. 2A-2D. As shown in these figures. As shown in FIG. 2Aa surface of the workpiece is irradiated by the laser beam 110 (or otherheat source) while the wire 140 is not in contact with the workpiece.The beam 110 creates a molten puddle A on the surface of the workpiece.In most applications the puddle A has a small area and the level ofpenetration is not that which would be required for other operations,such as welding or joining. Rather, the puddle A is created so as toprepare the surface of the workpiece to receive and cause sufficientbonding with a droplet from the wire 140. Thus, the beam density of thebeam 110 is to be such that only a small puddle is created on theworkpiece, without causing too much heat input into the workpiece or tocreate too large of a puddle. Upon creation of the puddle, a droplet Dis formed on the distal end of the wire 140 as the wire is advanced tothe puddle A so as to make contact with the puddle A, see FIG. 2B. Aftercontact, the droplet D is deposited onto the puddle A and workpiece (seeFIG. 2C). This process is repeated so as to create a desired workpiece.In FIG. 2D an optional step is shown in which the beam 110 is directedat the deposited droplet D after it is separated from the wire 140. Insuch embodiments, the beam 110 can be used to smooth the workpiecesurface and/or add additional heat to allow the droplet D to be fullyintegrated to the workpiece. Further, the beam can be used to provideadditional shaping of the workpiece.

FIG. 3 depicts an exemplary deposition process of the droplet D from thewire 140. The image on the left edge of FIG. 3 depicts the wire 140making contact with the workpiece. This contact is detected by the powersupply 170, which then provides a heating current to the wire 140 so asto heat the wire to at or near a melting temperature for the wire 140.The detection circuit used to detect contact between the workpiece andthe wire 140 can be constructed and operate like known detectioncircuits used in welding power supplies, and therefore a detailedexplanation of the circuit's operation and structure need not beprovided herein. The heating current from the power supply 170 is rampedup very quickly to provide the necessary energy to melt the droplet Dfrom the end of the wire 140. However, the current is controlledcarefully so that no arc is created between the wire 140 and theworkpiece. The creation of an arc could prove to be destructive to theworkpiece and is thus undesirable. Thus, the current is be controlled insuch a way (explained further below) so as to prevent the formation ofan arc.

Turning back to FIG. 3, the wire 140 makes contact with the workpieceand the power supply 170 provides a melting current (1). In someexemplary embodiments, an open circuit voltage OCV can be applied to thewire 140 prior to contact. After contact the current is ramped upquickly so to melt the end of the wire 140 to create a droplet D to bedeposited (2). The current also causes the wire 140 to neck down justabove the droplet D so as to allow for the separation of the droplet Dfrom the wire 140 (3). However, the current is controlled such thatwhile the wire 140 is necking down the current is either turned off orgreatly reduced so that when the wire 140 separates from the droplet Dno arc is created between the wire 140 and the workpiece (4). In someexemplary embodiments, the wire 140 can be retracted away from theworkpiece during and just prior to the breaking of the connectionbetween the droplet D and the wire 140. Because the droplet D is incontact with the puddle the surface tension of the puddle will aid inbreaking the droplet away from the wire 140. Once the droplet has beenseparated from the wire 140, the wire 140 is advanced to repeat theprocess to deposit another droplet. The wire 140 can be advanced at thesame positioned and/or the next droplet can be deposited at any desiredlocation.

As discussed previously, the laser beam 110 can also be utilized afterthe droplet D has been deposited on the workpiece to smooth or otherwiseshape the workpiece after deposition. Furthermore, the beam 110 canfurther be utilized during the deposition process. That is, in someexemplary embodiments the beam 110 can be used to add heat to the wire140 to aid in causing the formation of the droplet and/or the separationfrom the droplet D from the wire 140. This will be discussed furtherbelow.

Turning now to FIGS. 4A and 4B, each depict exemplary current waveformsthat can be utilized with exemplary embodiments of the presentinvention. In FIG. 4A, as can be seen, the waveform 400 has a pluralityof pulses 401, where each pulse represents the transfer of a droplet Dfrom the wire 140. A current pulse 401 is started at the time the wire140 makes contact. The current is then increased using a ramp up portion402 to a peak current level 401 which occurs just before the separationbetween the wire 140 and the droplet D. In this embodiment, during theramp up portion 402 the current continually increases to cause thedroplet to be formed and the necking down to occur in the wire beforeseparation. Before separation of the droplet D the current is rapidlydecreased during a ramp down portion 404 so that when separation occursno arc is created. In the waveform 400 of FIG. 4A the current is shutoff and drops to zero. However, in other exemplary embodiments of thepresent invention, the current can be dropped to a lower separationlevel and need not be shut off completely until the separation occurs.In such embodiments, the lower separation current level will continue toadd heat to the wire 140 thus aiding in the breaking off of the dropletD.

FIG. 4B depicts another exemplary embodiment of a current waveform 410.However, in this embodiment, the pulses 411 have a ramp up portion 402which utilizes a plurality of different ramp rate sections—as shown. Inthe embodiment shown, the ramp up portion 402 utilizes three differentramp rates 402A, 402B and 402C prior separation of the droplet D. Thefirst ramp rate 402A is a very steep and rapid current increase so as toquickly heat the wire 140 so as to start the melting process as soon aspossible. After the current reaches a first level 405, the current ramprate is changed to a second ramp rate 402B which is less than the firstramp rate. In some exemplary embodiments, the first current level is inthe range of 35 to 60% of the peak current level 413 for the pulse. Theramp rate 402B is less than the initial ramp rate 402A so as to aid inthe control of the current and prevent the formation of an arc, ormicroarcs. In the embodiment shown the second ramp rate is maintaineduntil the droplet D begins to form at the distal end of the wire 140. Inthe embodiment shown, once the droplet D starts to form the current ramprate is changed again to a third ramp rate 402C which is less than thesecond ramp rate 402B. Again, the decrease in the ramp rate is to allowfor added control of the current so as to prevent the inadvertentcreation of an arc. If the current was increasing too rapidly it can bedifficult (because of various issues such as system inductance) torapidly decrease the current when separation is detected and prevent thecreation of an arc. In some exemplary embodiments, the transition point407 between the second and third ramp rates is in the range of 50 to 80%of the peak current level 413 of the pulse 411. Like the pulses in FIG.4A, the current is significantly reduced when the separation of thedroplet is detected, which will be explained more fully below. It shouldalso be noted that other embodiments of the present invention can usedifferent ramp rate profiles without departing from the scope or spiritof the present invention. For example, the pulses can have two differentramp rate sections or can have more than three. Furthermore, the pulsescan utilize a ramp up which is constantly changing. For example, thecurrent can follow an inverse parabolic curve to the peak current level,or can utilize a combination of different configurations, where aconstant ramp rate is used from wire contact to the first current level405 and then an inverse parabolic curve can be used from that point.

As explained herein, the peak current levels of the pulses 401/411 is tobe below an arc generation level, but sufficient to melt off the dropletD during each pulse. Exemplary embodiments of the present invention canutilize different control methodologies for the peak current level. Insome exemplary embodiments, the peak current level can be a peak currentthreshold that is determined by various user input parameters that areinput prior to the additive operation. Such parameters include, wirematerial type, wire diameter, wire type (cored v. solid) anddroplets-per-inch (DPI). Of course, other parameters can also beutilized. Upon receiving this input information, the power supply 170and/or the controller 195 can utilize various control methodologies,such as a look-up table, and determine a peak current value for theoperation. Alternatively, the power supply 170 can monitor the outputcurrent, voltage, and/or power from the power supply 170 to determinewhen the separation will occur and control the current accordingly. Forexample, dv/dt, di/dt and/or dp/dt can be monitored (using a premonitioncircuit, or the like) and when separation is determined to occur thecurrent is turned off or reduced. This will be explained in more detailbelow.

The following is a discussion of the use and operation of exemplaryembodiments of the present invention. At the beginning of an additivemanufacturing process the power supply 170 can apply a sensing voltagebetween the wire 140 and a workpiece 115 via the power source 170. Thesensing voltage may be applied by the power supply 170 under the commandof the sensing and current controller 195. In some embodiments, theapplied sensing voltage does not provide enough energy to significantlyheat the wire 140. With the sensing voltage being applied, the distalend of the wire 140 is advanced toward the workpiece 115. The laser 120then emits a beam 110 to heat the surface of the workpiece 115 andcreate a puddle to receive the wire 140. The advancing is performed bythe wire feeder 150 and the contact with the workpiece is sensed whenthe distal end of the wire 140 first makes contact with the workpiece115. For example, the controller 195 may command the power supply 170 toprovide a very low level of current (e.g., 3 to 5 amps) through the wire140. The sensing may be accomplished by the sensing and currentcontroller 195 measuring a potential difference of about zero volts(e.g., 0.4V) between the wire 140 (e.g., via the contact tube 160) andthe workpiece 115. When the distal end of the filler wire 140 is shortedto the workpiece 115 (i.e., makes contact with the workpiece), asignificant voltage level (above zero volts) may not exist between thefiller wire 140 and the workpiece 115.

After contact, the power source 170 can be turned off over a definedtime interval (e.g., several milliseconds) in response to the sensing.Then the power source 170 can be turned back on at the end of thedefined time interval to apply a flow of heating current through thewire 140. Also, after contact is sensed the beam 110 can be turned offso as to not add too much heat to the puddle or the workpiece 115. Insome embodiments the laser beam 110 can stay on to aid in the heatingand separation of the droplet D. This will be discussed in more detailbelow.

In some exemplary embodiments of the present invention, the process caninclude stopping the advancing of the wire 140 in response to thesensing, restarting the advancing (i.e., re-advancing) of the wire 140at the end of the defined time interval, and verifying that the distalend of the filler wire 140 is still in contact with the workpiece 115before applying the flow of heating current, or after the heatingcurrent is being applied and the droplet D is being formed. The sensingand current controller 195 may command the wire feeder 150 to stopfeeding and command the system 100 to wait (e.g., several milliseconds).In such an embodiment, the sensing and current controller 195 isoperatively connected to the wire feeder 150 in order to command thewire feeder 150 to start and stop. The sensing and current controller195 may command the power supply 170 to apply the heating current pulsesto heat the wire 140 as described above, and this process can berepeated to deposit multiple droplets on a workpiece.

During operation, the high intensity energy source (e.g., laser device120) and the wire 140 can be moved along a workpiece 115 to provide thedroplets as desired. The motion controller 180 commands the robot 190 tomove the workpiece 115 in relation to the laser beam 110 and the wire140. The laser power supply 130 provides the power to operate the laserdevice 120 to form the laser beam 110. In further embodiments, the laserdevice 120 includes optics that can be adjusted to change the shape ofthe laser beam 110 on the impact surface of the workpiece. Embodimentscan use the beam shape to control the shape of the deposition process,that is by using a beam with a rectangular, elliptical or oval shape arelative narrow deposition can be made, thus making a thinner walledstructure. Further, the beam shape can be used to shape the depositionafter the droplet has separated from the consumable.

As discussed above, the pulse current is to be turned off or greatlyreduced when it is determined that the break between the wire 140 andthe droplet D is about to occur. This can be accomplished in a number ofdifferent ways. For example, such sensing may be accomplished by apremonition circuit within the sensing and current controller 195measuring a rate of change of one of a potential difference between(dv/dt), a current through (di/dt), a resistance between (dr/dt), or apower through (dp/dt) the wire 140 and the workpiece 115. When the rateof change exceeds a predefined value, the sensing and current controller195 formally predicts that loss of contact is about to occur. Suchpremonition circuits are well known in the art for arc welding, andtheir structure and function need not be described in detail herein.

When the distal end of the wire 140 becomes highly molten due toheating, the distal end will begin to pinch off from the wire 140 ontothe workpiece 115. For example, at that time, the potential differenceor voltage increases because the cross section of the distal end of thewire decreases rapidly as it is pinching off. Therefore, by measuringsuch a rate of change, the system 100 can anticipate when the distal endis about to pinch off and lose contact with the workpiece 115.

As explained previously, when the separation of the droplet is sensedthe current can be turned off or greatly reduced by the power supply170. For example, in some exemplary embodiments, the current is reducedto be in the range of 95 to 85% of the peak current value of the pulses.In exemplary embodiments, this current reduction occurs beforeseparation between the wire and the puddle.

For example, FIG. 5 illustrates an exemplary embodiment of a pair ofvoltage and current waveforms 510 and 520, respectively, associated withan additive manufacturing process of the present application. Thevoltage waveform 510 is measured by the sensing and current controller195 between the contact tube 160 and the workpiece 115. The currentwaveform 520 is measured by the sensing and current controller 195through the wire 140 and workpiece 115.

Whenever the distal end of the wire 140 is about to lose contact withthe workpiece 115, the rate of change of the voltage waveform 510 (i.e.,dv/dt) will exceed a predetermined threshold value, indicating thatpinch off is about to occur (see the slope at point 511 of the waveform510). As alternatives, a rate of change of current through (di/dt), arate of change of resistance between (dr/dt), or a rate of change ofpower through (dp/dt) the filler wire 140 and the workpiece 115 mayinstead be used to indicate that pinch off is about to occur. Such rateof change premonition techniques are well known in the art. At thatpoint in time, the sensing and current controller 195 will command thepower supply 170 to turn off (or at least greatly reduce) the flow ofcurrent through the wire 140.

When the sensing and current controller 195 senses that the distal endof the filler wire 140 again makes good contact with the workpiece 115after some time interval 530 (e.g., the voltage level drops back toabout zero volts at point 512), the sensing and current controller 195commands the power supply 170 to ramp up the flow of current (see ramp525) through the resistive filler wire 140 toward a predetermined outputcurrent level 550. The time interval 530 can be a predetermined timeinterval. In accordance with an embodiment of the present invention, theramping up starts from a set point value 540. This process repeats asthe energy source 120 and wire 140 move relative to the workpiece 115and as the wire 140 advances towards the workpiece 115 due to the wirefeeder 150 to deposit droplets at the desired locations. In this manner,an arc is prevented from forming between the distal end of the wire 140and the workpiece 115. Ramping of the heating current helps to preventinadvertently interpreting a rate of change of voltage as a pinch offcondition or an arcing condition when no such condition exists. Anylarge change of current may cause a faulty voltage reading to be takendue to the inductance in the heating circuit. When the current is rampedup gradually, the effect of inductance is reduced.

As explained previously, the power supply 170 provides a heating currentto the filler wire 140. The current passes from the contact tip 160 tothe wire 140 and then into the workpiece. This resistance heatingcurrent causes the wire 140 between the tip 160 and the workpiece toreach a temperature at or near the melting temperature of the fillerwire 140 being employed. Of course, the heat required to reach themelting temperature of the filler wire 140 will vary depending on thesize and chemistry of the wire 140. Accordingly, the heat to reach thedesired temperature of the wire during manufacturing will vary dependingon the wire 140. As will be further discussed below, the desiredoperating temperature for the filler wire can be a data input into thesystem so that the desired wire temperature is maintained duringmanufacturing. In any event, the temperature of the wire should be suchthat the wire 140 can deposit a droplet into the puddle.

In exemplary embodiments of the present invention, the power supply 170supplies a current which causes at least a portion of the distal end ofthe wire 140 at a temperature at or above 90% of its meltingtemperature. For example, when using a filler wire 140 having a meltingtemperature around 2,000° F., the temperature of the wire as it contactscan be approximately 1,800° F. Of course, it is understood that therespective melting temperatures and desired operational temperatureswill vary on at least the alloy, composition, diameter and feed rate ofthe filler wire 140. In further exemplary embodiments, portions of thewire are maintained at a temperature of the wire which is at or above95% of its melting temperature. Of course, in some embodiments, thedistal end of the wire is heated to at least 99% of its meltingtemperature by the heating current. Thus, when the heated droplet is incontact with the molten puddle created by the laser the heat from thepuddle can add heat to the wire 140 so as to fully create the moltendroplet at the end of the wire 140 so that the droplet is adhered to andstays with the puddle when the wire 140 is withdrawn. By maintaining thefiller wire 140 at a temperature close to or at its melting temperaturethe wire 140 is easily melted into or consumed into the puddle createdby the heat source/laser 120. That is, the wire 140 is of a temperaturewhich does not result in significantly quenching the puddle when thewire 140 makes contact with the puddle. Because of the high temperatureof the wire 140 the wire melts quickly when in contact with the puddle.In other exemplary embodiments, the wire can be heated to at or above75% of its melting temperature. However, when heating to a temperaturenear 75% it will be likely that additional heating will be necessary tomake the droplet sufficiently molten to transfer, which is furtherdiscussed below.

As described previously, in some exemplary embodiments, the completemelting of the wire 140 can be facilitated only by entry of the wire 140into the puddle. However, in other exemplary embodiments the wire 140can be completely melted by a combination of the heating current, thepuddle and the laser beam 110 impacting on a portion of the wire 140.That is, the heating/melting of the wire 140 can be aided by the laserbeam 110 such that the beam 110 contributes to the heating of the wire140. However, because many filler wires 140 are made of materials whichcan be reflective, if a reflective laser type is used the wire 140should be heated to a temperature such that its surface reflectivity isreduced, allowing the beam 110 to contribute to the heating/melting ofthe wire 140. In exemplary embodiments of this configuration, the wire140 and beam 110 intersect at the point at which the wire 140 enters thepuddle. This is shown in FIGS. 6A and 6B.

As shown in FIG. 6A, in some exemplary embodiments, the beam 110 can beused to aid in the deposition of droplets D onto the workpiece 115. Thatis, the beam 110 can be used to add heat to the distal end of the wire140 to create the molten droplet. In such embodiments, the heatingcurrent from the power supply can be kept at a level well below an arcgeneration level, thus ensuring that no arc will be created but properdroplet transfer can be achieved. In such embodiments the beam can bedirected such that it only impacts the droplet D, or in otherembodiments the beam 110 is large enough, shaped or rastered in afashion that it impacts at least a portion of the droplet and at leastsome of the puddle to continue to add heat to the puddle to receive thedroplet D. In exemplary embodiments of the energy density of the beam110 during this phase of the process is typically less than the energydensity of the beam when it is used to create the puddle on theworkpiece 115.

FIG. 6B depicts other exemplary embodiments of the present invention,where the beam 110 at the wire 140 just above the droplet to aid in itsseparation from the wire. In such embodiments, when it is sensed ordetermined that the wire 140 is necking down above the droplet, a beam110 is directed to the wire at the connection between the droplet D andthe wire 140 such that the beam 110 aids in separating the two. Suchembodiments aid in the prevention of an arc being generated because itis not needed to use the heating current to control the separation. Insome exemplary embodiments the beam 110 can come from the same laser 120that is used to create the puddle initially. However, in otherembodiments, the beam in FIG. 6B can also be emitted from a secondseparate laser which is also controlled by the controller 195. Thus, insuch embodiments when the controller and/or power supply detects theformation of a droplet or the imminent separation of the droplet D, theoutput current of the power supply 170 can be dropped while the laserbeam is directed to the wire 140 to cause the desired separation.

Turning now to FIG. 7, an exemplary embodiment of a heating system 700and contact tip assembly 707 is shown. It is generally noted thatembodiments of the present invention can utilize contact tips 160 andresistance heating systems that are known with respect to hot-wire orsome welding systems, without departing from the spirit or scope of thepresent invention. However, in other exemplary embodiments, a system 700as shown in FIG. 7 can be utilized. In this system 700 the contact tipassembly is comprised of two conductive portions 701 and 703 which areelectrically isolated from each by a insulation portion 705, which canbe made from any dielectric material. Of course, in other embodimentsthe insulation portion need not be present, so long as the tip portions701 and 703 are electrically isolated from each other. The system 700also includes a switching circuit 710 which switches the current pathto/from the power supply 170 between the contact tip portion 701 and theworkpiece 115. In some embodiments, it may be desirable to maintain thewire 140 at some threshold temperature during the manufacturing processwhile the wire 140 is not in contact with the workpiece 115. Without thewire 140 in contact with the workpiece 115 (e.g., during repositioning)no current will flow through the wire 140 and as such resistance heatingwill stop. Of course, residual heat will still be present but maydegrade quickly. This embodiment allows the wire 140 to be continuouslyheated even though it is not in contact with the workpiece 115. Asshown, one lead from the power supply is coupled to the an upper portion703 of the contact tip assembly 707. During operation, when the wire 140is in contact with the workpiece the switch 710 is positioned such thatthe current path is from the upper portion 703 through the wire 140 andthe workpiece, returning to the power supply 170 (dashed line in switch710). However, when the droplet D separates from the wire 140 andcontact with the workpiece 115 is broken the switch 710 is switched suchthat the current path if from contact tip portion 703 to contact tipportion 701 and back to the power supply 170. This allows at least someheating current to pass through the wire to continue to resistance heatthe wire at some background heating level. Because of such aconfiguration, the wire can be heated to its desired deposition levelquicker. This is especially the case if there has been a long durationbetween droplet depositions, during which the wire could cool. Thus, inexemplary embodiments the power supply 170 provides a current pulse orpulses (as generally described herein) to deposit droplets when theswitch 710 is in a first position (first current path) which directs thecurrent through the work piece, and then the power supply 170 provides abackground or heating current (which can be constant current forexample) when the switch is in a second position (second current path)that directs the current through both portions 701/703 of the contacttip to keep the wire heated in between droplet transfers. In someembodiments the switch can switch between each droplet transfer pulse,while in other embodiments the switch can switch after a plurality ofdroplet transfer pulses. In exemplary embodiments, thebackground/heating current level is selected to be a level which keepsthe wire at a desired—non melting—temperature. If the temperature is toohigh it can become difficult to push the wire to the puddle. In someexemplary embodiments, the background/heating current is in the range of10 to 70% of a peak current level reached during the droplet transferpulses.

It is noted that in FIG. 7 the switch 710 is shown external to powersupply 170. However, this depiction is just for clarity and the switchcan be internal to the power supply 170. Alternatively the switch canalso be internal to the contact tip assembly 707. The insulation portion705 can be made from any insulation type material or can simply be anisolative gap between the components 701 and 703. The switch can becontrolled by the controller 195 (as shown) or can be controlleddirectly by the power supply 170 depending on the desired configuration.

In other exemplary embodiments, a wire preheating device can bepositioned upstream of the assembly 707 which preheats the wire 140before it enters the tip 707. For example, the preheating device can bean induction heating device, which requires no current flow through thewire 140 to heat the wire 140. Of course, resistance heating systems canalso be used. This preheating device can be used to maintain the wire ata temperature as describe above. Further, the preheating can be used toalso remove any undesirable moisture from the wire 140 before it isdeposited (which is especially important when using Ti). Such preheatingsystems are generally known and need not be described in detail. Thepreheating device can be set to heat the wire 140 to a predeterminedtemperature before the wire enters the tip assembly 707, thus allowingthe current from the power supply 170 to be used to deliver enoughcurrent to complete the deposition process. It should be noted that thepreheating device should heat the wire 140 to a level which compromisesthe wire 140 such that the wire 140 can be properly pushed through thetip 707. That is, if the wire 140 is too hot it can become overlyflexible, which can compromise the responsiveness of the wire 140 whenbeing pushed.

FIG. 8A depicts an exemplary manufacturing current waveform 800 that canbe used with the system 700 in FIG. 7. In FIG. 8A a basic currentwaveform 800 is shown which comprises two components—a pulse portion 801and a background portion 803. The pulse portion is comprised of currentpulses used to deposit droplets as discussed herein. During these pulsesthe current is directed from the tip portion 703 through the workpiece115. However, during the background portion the current is directed fromthe tip portion 703 to portion 701 to heat the wire 140 when it is notin contact with the workpiece 115. Of course, it should be noted thatthe connections of the contact tip portions 701/703 to the positive andnegative power supply terminals as shown in FIG. 7 is exemplary and theconnections can be reversed based on the desired system set up andperformance. As explained previously, the background current level 803between pulses 801 is used to keep the wire at a sustained temperaturebetween droplet depositions. In some exemplary embodiments of thepresent invention, the background current keeps the wire 140 at atemperature which is in the range of 40 to 90% of the meltingtemperature of the wire 140. In other exemplary embodiments, the current803 keeps the wire 140 at a temperature in the range of 50 to 80% of themelting temperature of the wire 140.

It is further noted that it may not be desirable or necessary toconstantly switch to the background current between each pulse 801. Thiscould be particularly true during a high rate of droplet deposition.That is, during a high rate of droplet deposition, the wire 140 will bemaintained at a high level of temperature between droplets. Thus, insome exemplary embodiments, the switching to the background heatingcurrent (as described above) occurs only after a time duration hasexpired or when the duration between droplet pulses exceeds a thresholdtime. For example, in some embodiments, if the time between pulses is toexceed 1 s the system 700 will use the switching and background heatingcurrent as described above. That is, if the manufacturing methodutilized has a pulse frequency over a determined threshold frequencythen the above switching will be used. In exemplary embodiments of thepresent invention, this threshold is in the range of 0.5 to 2.5 sbetween pulses. In other embodiments, the system 700 can utilize a timer(internal to the controller 195 and/or the power supply 170) whichmonitors the time between pulses and if the time exceeds a thresholdamount the switching and background heating current described above willbe utilized. For example, if the system 700 determines that a latencybetween pulses has exceeded a threshold time limit (for example, 1 s)then the background heating current will be utilized to keep the wire140 at a desired temperature. Such an embodiment can be utilized inembodiments where the set threshold time has expired—that is, in realtime the system 700 determines that the time limit has expired, or canbe used when the system 700 predicts that the next pulse will not occurbefore the expiration of the time limit. For example, if the system 700(e.g., controller 195) determines that the next pulse will not occurbefore the expiration of the time limit (for example, due to movement ofthe workpiece 115 and/or wire 140 then the system 700 can immediatelyinitiate the switching and background heating current described above.In exemplary embodiments of the present invention, this durationthreshold is in the range of 0.5 to 2.5 seconds.

FIG. 8B depicts exemplary waveforms that can be used with exemplaryembodiments of the present invention to deposit a droplet as describedherein. The exemplary waveforms are for the transfer of a single dropletaccording to embodiments of the present invention. The waveforms shownare for laser power 810, wire feed speed 820, additive wire heatingcurrent 830, and voltage 840. It should be understood that the waveformsdepicted are intended to be exemplary and other embodiments of thepresent invention can use other waveforms having differentcharacteristics than shown or described herein. As shown, the droplettransfer cycle begins at 811, where the laser power is directed at theworkpiece and is increased 812 to a peak laser power level 813. After aduration Tp the laser creates a puddle on the workpiece at point 814. Atthis point the wire feeder starts to drive the additive wire towards thepuddle. The wire feed speed increases 821 to a peak wire feed speed 822after the puddle is created at 814. In exemplary embodiments of thepresent invention, the wire feed speed reaches its peak level 822 atapproximately the same time as the distal end of the wire makes contactwith the puddle 821′. However, in other exemplary embodiments the wirefeed speed can reach its peak level 822 prior to the wire makingcontact. As shown, at the same time the wire feeding process begins anopen circuit voltage is applied to the wire 841 so that it reaches apeak voltage level 842 at some point prior to wire making contact withthe puddle. Also, when the wire makes contact with the puddle theheating current 830 starts to flow (at point 831), and the voltage 840begins to drop 843. The voltage drops to a level 844 which is below anarc detection voltage 848, above which it is determined that an arcwould be created.

After the wire makes contact with the puddle the laser power 810, wirefeed speed 820 and current 830 are maintained at their respective peaklevels for a period of time Ta, during which a droplet of the wire isdeposited into the puddle. After the expiration of the deposition timeperiod Ta (at 815), which can be for a predetermined period of timecontrolled by the heating power supply (for example, using a timercircuit), the laser power is ramped down 816, along with the wire feedspeed 823. The heating current 830 is maintained at its peak level 833for a period of time after the expiration of the time period Ta (toppoint 834) and while the laser power and the wire feed speed are beingdecreased. This aids in separating the droplet from the wire. After thedroplet addition period Ta a wire retraction period Tr begins. After thecurrent 830 starts its ramp down 835 (starting at point 834) the wirefeed speed is reduced to zero (at point 827) and the wire feeder iscontrolled to retract the wire 824 at a peak retraction speed 825. Also,during the retraction period the current 830 is reduced to a burnbackcurrent level 836 which is used to provide burnback of the wire as it iswithdrawn from the puddle. During the wire retraction period Tr thecurrent 830 is maintained at the burnback current level 836 until thevoltage reaches or passes the arc detection voltage level 848 at point845, which is caused by the wire separating from the puddle (causingcurrent to drop and voltage to increase). When the voltage level 848 isreached, an arc suppression routine 847 is initiated to prevent an arcfrom being generated. During this time, the voltage climbs to a peaklevel 846.

The arc detection voltage level 848 is a predetermined level used by thepower supply and/or system controller to ensure that no arc is generatedbetween the retreating wire and the workpiece. The arc detection voltagelevel 848 is set by the power supply and/or system controller based onvarious user inputs, including, but not limited to, wire type, wirediameter, workpiece material type, droplet per inch input, droplet perminute input, etc.

When the arc detection voltage level 848 is reached (at 845) the current830 is shut off by the power supply (837) and the retraction of the wireis stopped (826) and the droplet transfer cycle ends at point 817, whenthe current 830 and wire feed speed 820 each reach 0. In the embodimentshown, the laser power 810 is also shown being shut off at the end ofthe cycle at point 817. In other exemplary embodiments, the laser power810 is shut off at the time the arc voltage threshold 848 is reached (atpoint 845). This cycle is then repeated for a plurality of dropletdeposits.

In some exemplary embodiments, (not shown) a laser power pulse can beinitiated between droplet transfer cycles (as shown In FIG. 8B) to aidin smoothing the workpiece or otherwise adding energy to the workpiecein between droplet transfers. For example, a laser power pulse can beinitiated in between each droplet transfer cycle, or in otherembodiments a laser power pulse can be initiated after a number n ofdroplet transfer cycles, as needed.

FIG. 9 depicts another exemplary system 900 of the present invention.The system 900 comprises a background power supply 170′ and a pulsingpower supply 170. This system operates very similar to that discussedabove, except that the background heating current is supplied by aseparate power supply 170′. Thus, in some embodiments the backgroundpower supply 170′ can provide a constant heating current duringmanufacturing and it is not necessary to provide the switching discussedabove. The pulsing power supply 170 operates as described otherwiseherein, except that its peak output current can be reduced because ofthe additional heating/current being provided by the power supply 170′.In such embodiments, the level of control or precision with the pulsepower supply 170 can be increased. That is, the pulse power supply 170can reach its peak pulse level quicker because of the lesser currentdemands on the power supply 170. Of course, the same will be true indecreasing current. Each of the power supplies 170/170′ can becontrolled by the controller 195, or can be configured in a master/slaverelationship, which is generally known. Furthermore, although thesepower supplies are shown separately for clarity, they can be housedwithin a single unit without departing from the spirit or scope of thepresent invention.

Also, shown in FIG. 9 is another contact tip assembly 900, havingconductive portions 901 and 905 and insulation portion 903. In thisembodiment, the conductive portion 905 is configured such that theheating current is transmitted as close to the exposed distal end of thewire 140 as possible. Such a configuration helps to ensure that theheating of the wire is maintained as close to the distal end aspossible, optimizing the effects of the background heating. In furtherembodiments, the stick out X of the distal end of the wire 140 from thecontact tip 910 is kept to a minimum distance. If the stick out X ismaintained too long the heating effects from the background heatingcurrent can be adversely affected. Thus, in some exemplary embodiments,the stick out X is maintained in the range of 0.1 to 0.5 inches. Inother exemplary embodiments, the stick out is maintained in the range of0.2 to 0.4 inches. Further, in additional exemplary embodiments, toobtain further benefits from the background heating, between dropletpulses the wire 140 is retracted fully, or near fully, into the contacttip 900, such that the stick out X is in the range of 0 to 0.15 inch.Such embodiments are capable of keeping the distal end of the wire 140at the desired background heating temperature without overheating otherportions of the wire 140 not close to the distal end. In other exemplaryembodiments, the stick out distance can be larger, particularly whenusing larger diameter consumables. For example, in some exemplaryembodiments, the stick out distance can be in the range of 0.75 to 2inches. Of course, in some other embodiments a longer stick out can beutilized.

Turning now to FIG. 10, another exemplary system 1000 is depicted, wherethe contact tip assembly 1010 is capable of delivering more than onewire 140/140′ to the workpiece 115. In some additive manufacturingoperations it may be desirable to utilize different wires for differentportions of the manufacture. The system 1000 allows for the switchingbetween different wires depending on what is desired for themanufacturing. Although not shown, each wire 140/140′ can be coupled toits own wire feeding apparatus to advance retract the respective wires140/140′ as needed during manufacturing. Thus, during manufacturing thecontroller 195 can position the contact tip assembly 1010 such that theappropriate wire is to be used for the manufacturing. For example, itmay be desirable to build a base with a first consumable 140 havingfirst properties, and then add to that base a layer made with the wire140′, having different properties to achieve a desired manufacturingresult. For example, the wires 140/140′ can have different sizes,shapes, and/or composition based on the desired manufacturingparameters. It should also be noted that although the contact tipassembly is shown with only two wires 140/140′, embodiments of thepresent invention, can utilize a contact tip assembly, or separatecontact tips to provide any number of varying consumables. Embodimentsof the present invention are not limited in this regard.

Furthermore, the contact tip assembly 1010 in FIG. 10 is shown such thatthe wires 140/140′ are not insulated from each other. In such anembodiment, the appropriate wire is advanced to the workpiece 115 fordeposition, and as such the current from the power supply 170 will bedirected through that wire—causing deposition. When the wire is to bechanged, the other wire is advanced while the other is retracted suchthat the current path is now through the other wire. In other exemplaryembodiments, the contact tip assembly 1010 can be constructed such thatthe wires 140/140′ are electrically isolated from each other. In suchembodiments, switching, like that discussed regarding FIG. 7, can beutilized. In some exemplary embodiments, a laser beam (not shown in FIG.10) can affect or otherwise alter the energy distribution in the puddlebetween the wires 140 and 140′ by being scanned between the two wires.This

The positioning and movement of the contact tip assembly 1010 relativeto the workpiece 115 can be effected by any number of means.Specifically, any known robotic or motion control systems can be usedwithout departing from the spirit or scope of the present invention.That is, the appropriate wire 140/140′ can be positioned using any knownmeans or methods, including robotic systems, and can be controlled bycontroller 195. For example, the contact tip assembly 1010 can comprisethree or more different wires and be constructed and utilized similar toknown computer numerical control (CNC) machining heads which are rotatedand positioned to allow for the utilization of appropriate tooling. Suchsystems and control logic can be utilized in embodiments of the presentinvention to provide the desired positioning of the desired wire.

The wires (or consumables) used with embodiments of the presentinvention are to have a size and chemistry as needed for a particularmanufacturing operation. Typically, the wires have a circularcross-section, by other embodiments are not limited in this way. Otherexemplary embodiments can utilize wires having a non-circularcross-section based on the manufacturing method and manufacturingprocess. For example, the wires can have a polygonal, oval, orelliptical shape to achieve a desired manufacturing criteria. Circularcross-section wires can have a diameter in the range of 0.010 to 0.045inch. Of course, larger ranges (for example, up to 5 mm) can be used ifdesired, but the droplet control may become more difficult as thediameter increases. Because of the use of the laser and the heatingcontrol methodologies describe herein, embodiments of the presentinvention can provide very precise manufacturing. This is particularlytrue with embodiments that utilize smaller diameter wires, such as inthe range of 0.010 to 0.020 inch. By using such small diameters a largeDPI (droplets per inch) ratio can be achieved, thus providing highlyaccurate and detailed manufacturing. The chemistry of the wires is to beselected to provide the desired properties for the manufacturedcomponent. Further, the wire(s) utilized can either have a solid ormetal-core configuration. Cored wires can be used to create a compositematerial construction. For example, a cored wire having an aluminumsheath and an aluminum oxide core can be used.

It is further noted that because no arc is used with the processesdescribe herein, most applications of the present invention will notrequire shielding gas of any kind. However, in some applications it maybe desirable to use a shielding gas to prevent oxidation, or for otherpurposes.

FIG. 11 depicts yet another exemplary embodiment of the presentinvention. FIG. 11 shows an embodiment similar to that as shown inFIG. 1. However, certain components and connections are not depicted forclarity. FIG. 1 depicts a system 1100 in which a thermal sensor 1110 isutilized to monitor the temperature of the wire 140. The thermal sensor1110 can be of any known type capable of detecting the temperature ofthe wire 140. The sensor 1110 can make contact with the wire 140 or canbe coupled to the tip 160 so as to detect the temperature of the wire.In a further exemplary embodiment of the present invention, the sensor1110 is a type which uses a laser or infrared beam which is capable ofdetecting the temperature of a small object—such as the diameter of afiller wire—without contacting the wire 140. In such an embodiment thesensor 1110 is positioned such that the temperature of the wire 140 canbe detected at the stick out of the wire 140—that is at some pointbetween the end of the tip 160 and the puddle. The sensor 1110 shouldalso be positioned such that the sensor 1110 for the wire 140 does notsense the puddle temperature.

The sensor 1110 is coupled to the sensing and control unit 195(discussed with regard to FIG. 1) such that temperature feedbackinformation can be provided to the power supply 170 and/or the laserpower supply 130 so that the control of the system 1100 can beoptimized. For example, the power or current output of the power supply170 can be adjusted based on at least the feedback from the sensor 1110.That is, in an embodiment of the present invention either the user caninput a desired temperature setting (for a given manufacturing operationand/or wire 140) or the sensing and control unit 195 can set a desiredtemperature based on other user input data (electrode type, etc.) andthen the sensing and control unit 195 would control at least the powersupply 170 to maintain that desired temperature.

In such an embodiment it is possible to account for heating of the wire140 that may occur due to the laser beam 110 impacting on the wire 140before the wire enters the puddle. In embodiments of the invention thetemperature of the wire 140 can be controlled only via power supply 170by controlling the current in the wire 140. However, as explained above,in other embodiments at least some of the heating of the wire 140 cancome from the laser beam 110 impinging on at least a part of the wire140. As such, the current or power from the power supply 170 alone maynot be representative of the temperature of the wire 140. As such,utilization of the sensor 1110 can aid in regulating the temperature ofthe wire 140 through control of the power supply 170 and/or the laserpower supply 130.

In a further exemplary embodiment (also shown in FIG. 11) a temperaturesensor 1120 is directed to sense the temperature of the puddle. In thisembodiment the temperature of the puddle is also coupled to the sensingand control unit 195. However, in another exemplary embodiment, thesensor 1120 can be coupled directly to the laser power supply 130.Feedback from the sensor 1120 is used to control output from laser powersupply 130/laser 120. That is, the energy density of the laser beam 110can be modified to ensure that the desired puddle temperature isachieved.

In yet a further exemplary embodiment of the invention, rather thandirecting the sensor 1120 at the puddle, it can be directed at an areaof the workpiece 115 adjacent the puddle. Specifically, it may bedesirable to ensure that the heat input to the workpiece 115 adjacentthe deposition location is minimized. The sensor 1120 can be positionedto monitor this temperature sensitive area such that a thresholdtemperature is not exceeded adjacent the deposition location. Forexample, the sensor 1120 can monitor the workpiece temperature andreduce the energy density of the beam 110 based on the sensedtemperature. Such a configuration would ensure that the heat inputadjacent the deposition location would not exceed a desired threshold.Such an embodiment can be utilized in precision manufacturing operationswhere heat input into the workpiece is important.

In another exemplary embodiment of the present invention, the sensingand control unit 195 can be coupled to a feed force detection unit (notshown) which is coupled to the wire feeding mechanism (not shown—but see150 in FIG. 1). The feed force detection units are known and detect thefeed force being applied to the wire 140 as it is being fed to theworkpiece 115. For example, such a detection unit can monitor the torquebeing applied by a wire feeding motor in the wire feeder 150, and thusparameters related to the contact between the distal end of the wire 140and the workpiece 115. This, coupled with current and/or voltagemonitoring, can be used to stop the feeding of the wire after contact ismade with the puddle to allow for the separation of the droplet D. Ofcourse, as indicated previously, the controller 195 can just use voltageand/or current sensing to detect contact between the wire 140 and thepuddle and can use this information alone to stop wire feeding ifdesired when contact is made.

In a further exemplary embodiment, the sensor 1120 can be used to detectthe size of the puddle area on the workpiece. In such embodiments, thesensor 1120 can be either a heat sensor or a visual sensor and used tomonitor an edge of the puddle to monitor the size and/or position of thepuddle. The controller 195 then uses the detected puddle information tocontrol the operation of the system as described above.

The following provides further discussion regarding the control of theheating pulse current that can be used with various embodiments of thepresent invention. As mentioned previously, when the distal end of thewire 140 is in contact with puddle/workpiece 115 the voltage between thetwo can be at or near 0 volts. However, in other exemplary embodimentsof the present invention it is possible to provide a current at such alevel so that a voltage level above 0 volts is attained without an arcbeing created. By utilizing higher currents values it is possible tohave the wire 140 reach high temperatures, closer to an electrode'smelting temperature, at a quicker rate. This allows the manufacturingprocess to proceed faster. In exemplary embodiments of the presentinvention, the power supply 170 monitors the voltage and as the voltagereaches or approaches a voltage value at some point above 0 volts thepower supply 170 stops flowing current to the wire 140 to ensure that noarc is created. The voltage threshold level will typically vary, atleast in part, due to the type of wire 140 being used. For example, insome exemplary embodiments of the present invention the thresholdvoltage level is at or below 6 volts. In another exemplary embodiment,the threshold level is at or below 9 volts. In a further exemplaryembodiment, the threshold level is at or below 14 volts, and in anadditional exemplary embodiment; the threshold level is at or below 16volts. For example, when using mild steel wires the threshold level forvoltage will be of the lower type, while wires which are for stainlesssteel manufacturing can handle the higher voltage before an arc iscreated. Thus, such a system can monitor the voltage and control theheating current by comparing the voltage to a voltage set point, suchthat when the voltage exceeds, or is predicted to exceed the voltage setpoint, the current is shut off or reduced.

In further exemplary embodiments, rather than maintaining a voltagelevel below a threshold, such as above, the voltage is maintained in anoperational range. In such an embodiment, it is desirable to maintainthe voltage above a minimum amount—ensuring a high enough current tomaintain the wire at or near its melting temperature but below a voltagelevel such that no arc is created. For example, the voltage can bemaintained in a range of 1 to 16 volts. In a further exemplaryembodiment the voltage is maintained in a range of 6 to 9 volts. Inanother example, the voltage can be maintained between 12 and 16 volts.Of course, the desired operational range can be affected by the wire 140used for the manufacturing operation, such that a range (or threshold)used for an operation is selected, at least in part, based on the wireused or characteristics of the wire used. In utilizing such a range thebottom of the range is set to a voltage at which the wire can besufficiently deposited in the puddle and the upper limit of the range isset to a voltage such that the creation of an arc is avoided.

As described previously, as the voltage exceeds a desired thresholdvoltage the heating current is shut off by the power supply 170 suchthat no arc is created. Thus, in such embodiments the current can bedriven based on a predetermined or selected ramp rate (or ramp rates)until the voltage threshold is reached and then the current is shut offor reduced to prevent arcing.

In the many embodiments described above the power supply 170 containscircuitry which is utilized to monitor and maintain the voltage asdescribed above. The construction of such type of circuitry is known tothose in the industry. However, traditionally such circuitry has beenutilized to maintain voltage above a certain threshold for arc welding.

As explained previously, the heating current can also be monitoredand/or regulated by the power supply 170. This can be done in additionto monitoring voltage, power, or some level of a voltage/amperagecharacteristic as an alternative. That is, the current can be driven to,or maintained, at a desired level to ensure that the wire 140 ismaintained at an appropriate temperature—for proper deposition in thepuddle, but yet below an arc generation current level. For example, insuch an embodiment the voltage and/or the current are being monitored toensure that either one or both are within a specified range or below adesired threshold. The power supply 170 then regulates the currentsupplied to ensure that no arc is created but the desired operationalparameters are maintained.

In yet a further exemplary embodiment of the present invention, theheating power (V×I) can also be monitored and regulated by the powersupply 170. Specifically, in such embodiments the voltage and currentfor the heating power is monitored to be maintained at a desired level,or in a desired range. Thus, the power supply not only regulates thevoltage or current to the wire, but can regulate both the current andthe voltage. In such embodiments the heating power to the wire can beset to an upper threshold level or an optimal operational range suchthat the power is to be maintained either below the threshold level orwithin the desired range (similar to that discussed above regarding thevoltage). Again, the threshold or range settings will be based oncharacteristics of the wire and manufacturing being performed, and canbe based—at least in part—on the filler wire selected. For example, itmay be determined that an optimal power setting for a mild steelelectrode having a diameter of 0.045″ is in the range of 1950 to 2,050watts. The power supply will regulate the voltage and current such thatthe power is driven to this operational range. Similarly, if the powerthreshold is set at 2,000 watts, the power supply will regulate thevoltage and current so that the power level does not exceed but is closeto this threshold.

In further exemplary embodiments of the present invention, the powersupply 170 contains circuits which monitor the rate of change of theheating voltage (dv/dt), current (di/dt), and or power (dp/dt). Suchcircuits are often called premonition circuits and their generalconstruction is known. In such embodiments, the rate of change of thevoltage, current and/or power is monitored such that if the rate ofchange exceeds a certain threshold the heating current to the wire 140is turned off.

In other exemplary embodiments of the present invention, the change ofresistance (dr/dt) is also monitored. In such an embodiment, theresistance in the wire between the contact tip and the puddle ismonitored. As explained previously, as the wire heats up it starts toneck down and this can create a tendency to form an arc, during whichtime the resistance in the wire increases exponentially. When thisincrease is detected the output of the power supply is turned off asdescribed herein to ensure an arc is not created. Embodiments regulatethe voltage, current, or both, to ensure that the resistance in the wireis maintained at a desired level.

FIG. 12 depicts an exemplary system 1200 which can be used to providethe heating current to wire 140. (It should be noted that the lasersystem is not shown for clarity). The system 1200 is shown having apower supply 1210 (which can be of a type similar to that shown as 170in FIG. 1). The power supply 1210 can be of a known welding/heatingpower supply construction, such as an inverter-type power supply.Because the design, operation and construction of such power suppliesare known they will not be discussed in detail herein. The power supply1210 contains a user input 1220 which allows a user to input dataincluding, but not limited to: wire type, wire diameter, a desired powerlevel, a desired wire temperature, voltage and/or current level. Ofcourse, other input parameters can be utilized as needed. The userinterface 1220 is coupled to a CPU/controller 1230 which receives theuser input data and uses this information to create the neededoperational set points or ranges for the power module 1250. The powermodule 1250 can be of any known type or construction, including aninverter or transformer type module. It is noted that some of thesecomponents, such as the user input 1220 can also be found on thecontroller 195.

The CPU/controller 1230 can determine the desired operational parametersin any number of ways, including using a lookup table, In such anembodiment, the CPU/controller 1230 utilizes the input data, forexample, wire diameter and wire type to determine the desired currentlevel for the output (to appropriately heat the wire 140) and thethreshold voltage or power level (or the acceptable operating range ofvoltage or power). This is because the needed current to heat the wire140 to the appropriate temperature will be based on at least the inputparameters. That is, an aluminum wire 140 may have a lower meltingtemperature than a mild steel electrode, and thus requires lesscurrent/power to melt the wire 140. Additionally, a smaller diameterwire 140 will require less current/power than a larger diameter wire.Also, as the manufacturing speed increases (and accordingly thedeposition rate) the needed current/power level to melt the wire may behigher.

Similarly, the input data will be used by the CPU/controller 1230 todetermine the voltage/power thresholds and/or ranges (e.g., power,current, and/or voltage) for operation such that the creation of an arcis avoided. For example, for a mild steel electrode having a diameter of0.045 inches can have a voltage range setting of 6 to 9 volts, where thepower module 1250 is driven to maintain the voltage between 6 to 9volts. In such an embodiment, the current, voltage, and/or power aredriven to maintain a minimum of 6 volts—which ensures that thecurrent/power is sufficiently high to appropriately heat theelectrode—and keep the voltage at or below 9 volts to ensure that no arcis created and that a melting temperature of the wire 140 is notexceeded. Of course, other set point parameters, such as voltage,current, power, or resistance rate changes can also be set by theCPU/controller 1230 as desired.

As shown, a positive terminal 1221 of the power supply 1210 is coupledto the contact tip 160 of the system and a negative terminal of thepower supply is coupled to the workpiece W. Thus, a heating current issupplied through the positive terminal 1221 to the wire 140 and returnedthrough the negative terminal 1222. Such a configuration is generallyknown.

A feedback sense lead 1223 is also coupled to the power supply 1210.This feedback sense lead can monitor voltage and deliver the detectedvoltage to a voltage detection circuit 1240. The voltage detectioncircuit 1240 communicates the detected voltage and/or detected voltagerate of change to the CPU/controller 1230 which controls the operationof the module 1250 accordingly. For example, if the voltage detected isbelow a desired operational range, the CPU/controller 1230 instructs themodule 1250 to increase its output (current, voltage, and/or power)until the detected voltage is within the desired operational range.Similarly, if the detected voltage is at or above a desired thresholdthe CPU/controller 1230 instructs the module 1250 to shut off the flowof current to the tip 160 so that an arc is not created. If the voltagedrops below the desired threshold the CPU/controller 1230 instructs themodule 1250 to supply a current or voltage, or both to continue themanufacturing process. Of course, the CPU/controller 1230 can alsoinstruct the module 1250 to maintain or supply a desired power level. Ofcourse, a similar current detection circuit can be utilized, and is notshown for clarity. Such detection circuits are generally known.

It is noted that the detection circuit 1240 and CPU/controller 1230 canhave a similar construction and operation as the controller 195 shown inFIG. 1. In exemplary embodiments of the present invention, thesampling/detection rate is at least 10 KHz. In other exemplaryembodiments, the detection/sampling rate is in the range of 100 to 200KHz.

In each of FIGS. 1 and 11 the laser power supply 130, power supply 170and sensing and control unit 195 are shown separately for clarity.However, in embodiments of the invention these components can be madeintegral into a single system. Aspects of the present invention do notrequire the individually discussed components above to be maintained asseparately physical units or stand-alone structures.

In some exemplary embodiments described above, the system can be used insuch a fashion to combine cladding and droplet deposition as describedabove. That is, during the construction of a workpiece it may not alwaysbe required to have high precision construction, for example during thecreation of a supporting substrate. During this phase of construction ahot wire cladding process can be used. Such a process (and systems) aredescribed in U.S. application Ser. No. 13/212,025, which is incorporatedherein by reference in its entirety. More specifically, this applicationis incorporated fully herein to the extent it described the systems,methods of use, control methodology, etc. used to deposit material usinga hot-wire system in a cladding or other type of overlaying operation.Then, when a more precise deposition methodology is desired toconstruction the workpiece the controller 195 switches to a dropletdeposition method, as described above. The controller 195 can controlthe systems described herein to utilize droplet deposition and claddingdeposition processes as needed to achieve the desired construction.

Embodiments described above can achieve high speed droplet deposition.For example, embodiments of the present invention can achieve dropletdeposition in the range of 10 to 200 Hz. Of course, other ranges can beachieved depending on the parameters of the operation. In someembodiments, the droplet deposition frequency can be higher than 200 Hz,depending on some of the parameters of the operation. For example,larger diameter wires will typically use a deposition frequency lessthan 200 Hz, whereas smaller diameter wires, such as in the range of0.010 to 0.020 inch can achieve faster frequencies. Other factors thataffect the droplet deposition frequency include laser power, workpiecesize and shape, wire size, wire type, travel speed, etc.

FIG. 13 depicts another exemplary embodiment of the present invention,where a plurality of consumables can be deposited at the same time. Inthe embodiment shown four consumables are being deposited. However,embodiments are not limited in this regard as any number can beutilized. In such embodiments, the buildup of the workpiece can beaccelerated as multiple consumables can be deposited in a single pass.As will be described further below, other advantages to such aconfiguration are also attained.

As shown in the exemplary system 1300, a contact tip assembly 1305houses a plurality of contact tips 1303, 1303′, 1303″, 1303′″, each ofwhich deliver a consumable 140, 140′, 140″, 140″ (respectively) to theworkpiece being created. In the shown embodiment, each of the contacttips are electrically isolated from each other such that each contacttip can receive a separate current waveform to be used for deposition.For example, as shown in the exemplary system 1300, a power supply iselectrically coupled to each contact tip so as to separately provide andcontrol the current waveform for each consumable. As a note the systemcontroller 195 is not shown in this Figure. However, the system 1300 caninclude a controller 195 as described previously herein to control theoperation of each of the power supplies, as well as the operation. Inthe embodiment shown, a power supply system 1310 is shown havingdistinct individual power supply modules P.S. #1 through P.S. #4 (1311,1312, 1313 and 1314), each of which is capable of outputting a distinctcurrent to deposit the consumables. Each of the currents can be similarto the exemplary waveforms described herein, having differentparameters, etc. Further, each of the power supplies 1311-1314 can beconstructed and operated similar to the power supplies discussed hereinwith respect to FIGS. 1 through 12. In some exemplary embodiments, eachof the power supplies 1311-1314 can be separate power supply modules ina single power supply system 1310—for example being within a singlehousing. In other exemplary embodiments, each of the power supplies1311-1314 can be separate and distinct power supplies, which can belinked to each other to synchronize, and otherwise control, theiroperation.

During operation, the system 1300 can create a workpiece on a substrateS by depositing multiple layers in a single pass. In the FIG. 13embodiment, each consumable 140-140′″ is creating a separate layer L#1,L#2, L#3, L#4, where each trailing consumable is creating a layer on topof the preceding layer. This is accomplished by having the tips1303-1303′″ in line with each other in the travel direction as shown.During deposition, the leading consumable 140 is deposited onto thesubstrate S creating the first layer L#1, and the trailing consumable140′ is deposited onto the previous layer L#1, to create a second layerL#2—and so on. To allow for the creation of the layers, at differentheights, the contact tip assembly 1305 can position the contact tips aredifferent heights relative to the substrate S surface. As shown in FIG.13, the contact tips have a staggered or stepped formation to allow forthe stacking of the layers. In other exemplary embodiments, the contacttips can be at the same level, relative to the surface, but thestick-out distance of the consumables can be adjusted appropriately toachieve the desired stacking of layers.

In exemplary embodiments of the present invention, the spacing betweenthe consumables (in the travel direction) is such that the subsequentlayers can be adequately constructed on the previously deposited layer.In exemplary embodiments, the spacing is such that the consumables arenot deposited in the same puddle. That is, the trailing consumable doesnot make contact with the preceding puddle. However, the respectivepuddles are adjacent to each other on the workpiece. That is, inexemplary embodiments, while the puddles are adjacent or near to eachother, their molten portions do not contact each other. Of course, thepuddles can be at different elevation levels (see e.g., FIG. 13), andthe temperature of the deposit between the puddles can be very high, butthe molten portions are not contacting each other.

It is noted that although not shown in FIG. 13, the system 1300 can alsouse a laser or heat input system as described in the above exemplaryembodiments. Specifically, the system 1300 can use a laser to create amolten puddle and/or aid in melting the consumable. In some exemplaryembodiments, individual beams can be directed to each separateconsumable deposition process and be controlled individually for eachrespective deposition process. The individual beams can be generatedfrom separate laser emitting devices, or can come from a single laseremitting device, but is divided into separate beams via optics and lasersplitters, etc. The deposition of each individual consumable 140 to140′″ can be controlled as described previously. Alternatively, in otherexemplary embodiments a single laser/heat source can be used which israstered between consumables during the deposition process to providethe desired heat input for each consumable deposition process. Forexample, a laser beam can be rastered to the deposition of eachconsumable 140-140′″ and the interaction time at each consumablelocation is controlled to achieve the desired heat input for eachdeposition operation.

In exemplary embodiments of the present invention, the type, size andcomposition of the consumables 140-140′″ is chosen based on the desiredproperties of the workpiece. In some embodiments, each of theconsumables 140-140′″ are the same, having the same diameter andcomposition. However, in other exemplary embodiments, the consumablescan have different properties. For example, the consumables 140-140′″can have different diameters, such that the layers L#1-L#4 can be madewith different widths, by using varying diameter consumables. Moreover,the consumables can have different compositions to allow for thecreation of a workpiece having varying physical/compositionalcharacteristics at different places. In such embodiments, thecomposition of a workpiece being manufactured can be changed “on thefly”. That is, a first material can be used to make certain portions ofa workpiece—using some contact tips—and then without stopping the systemcan deposition a different or additional materials—as desired.

For example, exemplary embodiments of the present invention can be usedto manufacture a structure or workpiece using a mixture of stainlesssteel and mild steel. Further, such structures can be built with anickel material being added. Of course, these are simply exemplary andembodiments of the present invention allow for the mixture of multiplematerials to be build a desired structure. In other exemplaryembodiments, a band or layer of non-magnetic material/metal can be addedto the workpiece for various reasons, including measurement of theworkpiece. Differing materials can also be used to convert a material toan austenitic stainless steel.

In addition to varying properties/types of the consumables, embodimentsof the present invention can deliver the consumables 140-140′″ withvarying wire feed speeds. That is, in some embodiments, the wire feedspeed for all of the consumables is the same. However, in otherembodiments it may be desirable to vary the wire feed speeds. This canbe done via the controller 195 and the respective wire feeding systemsof the consumables (not shown for clarity). By varying the respectivewire feed speeds, the physical properties of the workpiece being createdcan be affected. For example, it may be desirable to have at least oneof the layers L#1 to L#4 thinner than the others. In such embodiments,the wire feed speed for the respective consumable of the thinner layercan be slowed, thus resulting in a thinner layer.

Moreover, in exemplary embodiments different current waveforms can beprovided to the consumables 140-140′″. In the system 1300 shown thereare separate power supply modules 1311-1314 providing the respectivedeposition currents to the consumables. In some embodiments, each of thecurrents can be the same, while in other embodiments the currentwaveforms can be different—having different frequencies, peak currentlevels, etc. This can be the case when using differing wire feed speedsand/or differing consumables to ensure proper deposition.

By varying aspects of the deposition of any of the consumables 140-140′″the system 1300 provides significant flexibility in the creation of thelayers L#1-L#4. That is, in exemplary embodiments any one, or acombination of, consumable type, composition, diameter, wire feed speed,and deposition current waveform can be varied, relative to anotherconsumable, to achieve a desired property of a layer or the depositionprocess. Thus, embodiments of the present invention allow for the rapidconstruction or build-up of a workpiece with a significant amount offlexibility and precision in the construction of any layer or thedeposition of a consumable. That is, different layers can have differentthicknesses, widths, shapes, etc. based on the use of varyingdeposition/consumable properties.

FIG. 14 depicts another view of the system 1300 shown in FIG. 13. Asshown, and discussed above, the contact tips 1303 and 1303′ are mountedto the contact tip assembly 1305 which orients, holds and moves thecontact tips as desired. Further, as discussed above, the contact tipsare held in a staggered or stepped pattern to allow for the creation ofthe layers on top of each other—as shown. In such embodiments, thestick-out X for each of the respective consumables 140, 140′ ismaintained as generally the same distance. However, in other embodimentsthis need not be the case. That is, the stick-out distance X for eachrespective consumable 140,140′ can be varied to achieve a desireddeposition performance. In fact, in some embodiments, the contact tips1303,1303′ can be secured such that their respective distal end facesare co-planar with each other, relative to the surface of the substrateS. In such an arrangement the stick-out distance X of trailingconsumables (e.g., 140′) would be less than each preceding consumable(e.g., 140) when layers L#1, L#2 are being constructed as shown.

Further, as shown, in some embodiments the contact tips 1303,1303′ aremovable within the contact tip assembly 1305. In such embodiments, anactuator mechanism 1320, such as rollers, an actuator, etc. can be usedto move the contact tips 1303,1303′ in and out of the contact tipassembly 1305 to provide the desired stick-out and/or geometry of theworkpiece being constructed. The actuators 1320 can also be controlledby the controller 195 (not in in FIG. 14) such that the contact tips canbe moved “on the fly” during a deposition process. For example, duringdeposition the relative height of the contact tips and/or stick outdistance X of the consumables can be adjusted to achieve the desiredgeometry of the workpiece being manufactured. This movement can becreated a number of ways as described above. For example, servos, motorcontrol rollers, linear actuators, etc. can be used to move the contacttips as desired. Such control enhances the flexibility of themanufacturing capabilities of the system 1300.

It is noted, that while FIGS. 13 and 14 depict the contact tip assembly1305 such that the consumables are in line in a travel/depositiondirection, the contact tip assembly 1305 can also be positioned in alateral configuration where the contact tips are in a line which isnormal to the travel direction. That is, the contact tips can beside-by-side to provide a wide material deposition. In such anembodiment, the consumables are deposited adjacent to each other, ratherthan on top of each other as shown in the FIGS. 13 and 14. Of course, inother exemplary embodiments, the contact tip assembly 1305 can beoriented such that the contact tips are oriented at an angle relative tothe travel direction. Embodiments of the present invention are notlimited in this regard.

FIG. 15 depicts another exemplary embodiment, where the contact tipassembly 1305 is also rotatable relative to the travel direction of thedeposition process. As shown in this top down view, in a first positionA the consumable are deposited in line as shown in FIGS. 13 and 14. Asthe contact tip assembly 1305 continues to travel, it is rotated to anew position B such that the deposition of the layers changes shape, asshown. The contact tip assembly 1305 can be controlled and rotated byany known devices and methods, such as by using a step motor, motor, orany other known system (for example, those systems used in roboticwelding to control/facilitate movement and rotation). The controller 195can be used to control the rotation/movement of the contact tip assembly1305 relative to the substrate S. By having the assembly 1305 rotatable,a shape of the workpiece can be created as needed. For example, a wallthickness of a workpiece can be increased/decreased as needed. Further,during the rotation of the assembly 1305 any one, or a combination of,the wire feed speed, the current waveform, stick-out and/or contact tipposition of for any of the consumables can be adjusted. For example, asshown in FIG. 15, prior to position A only one of the consumables isbeing deposited to create the layer L#1, as shown. This can be theleading consumable in the assembly. As the assembly 1305 is turned, asecond consumable 140′ begins being deposited for a second layer L#2such that the deposit L#2 couples to and adds onto the first layer L#1.This can be down without adding undesired height, but just to increasethe width of the workpiece being created. Similarly, the subsequentconsumables 140″ and 140′″ can begin deposition similarly andsequentially as the assembly 1305 is rotated to the desired position B.Similarly, this motion can be used to create a ledge or overhang on theworkpiece without the need for additional support for the overhang. Insuch embodiments, the rotation of the assembly 1305 and the adjustmentof the deposition of any one, or all, of the consumables (as describedabove) can allow an overhang to be created relatively easily. Forexample, the adjustment of the feed rate and/or the stick out/contacttip depth positioning can allow for the creation of a ledge relativelysimply.

Therefore, the system 1300 greatly increases the manufacturingflexibility of the additive manufacturing processes and systemsdescribed herein.

FIGS. 16, 17A-C and 18A depict exemplary embodiments of a substrate 1600that can be used with the methods and systems described herein. Thesubstrate 1600 is electrically conductive—so as to provide for a currentpath for the deposition current/waveform—but also has a non-bondingsurface 1610 such that it is relatively easy to remove a workpiece fromthe substrate 1600 after completion of the manufacturing process.

Typically, in additive manufacturing, the workpiece being constructed isplaced on a substrate or surface which is conductive so as to provide aproper current path for the consumable heating current. However, becausethe substrate is conductive (i.e. metallic) the workpiece becomes bondedwith the substrate. That is, during the initial manufacture of theworkpiece, the initially created layers become adhered to the substratevia the deposition process. Because of this, an additional processingstep is needed to remove the workpiece from the substrate andpotentially remove some of the substrate material from the finalworkpiece. This adds additional processing as well as creates apotential risk of damage to the workpiece. It is understood by those ofordinary skill in the art that bonding between a workpiece and thesubstrate typically occurs when there is fusion between the workpieceand the substrate, such that the material from the workpiece mixes withthe material of the substrate in an admixture zone on thesubstrate—consistent with joining technologies. Embodiments of thepresent invention address this issue.

FIG. 16 depicts an exemplary substrate 1600 which is made from aconductive material, which allows current to pass through it, butprevents the workpiece 110 from bonding to it. For example, in someexemplary embodiments the substrate can be made from copper or graphite,which are conductive but will not bond with aluminum or steelworkpieces. In additional exemplary embodiments the substrate 1600 canbe made as a matrix of a number of different materials. For example, thesubstrate 1600 can be made from a non-electrically conductive ceramic orclay material matrix material which has a conductive (e.g., metallic)material distributed within the ceramic or clay matrix so as to create aconductive path. As shown in FIG. 16, the non-conductive matrix 1603 hasconductive particles 1605 distributed throughout it such an electricalcurrent path can be made from the surface 1610 to a ground point 1625—towhich a lead from a power supply can be connected. In some exemplaryembodiments, the substrate 1600 can be primarily ceramic with copperparticles 1605 distributed throughout, having a sufficient amount ofcopper to provide a copper density that allows an electrical current tobe transferred from the workpiece surface of the substrate to anotherlocation of the substrate, to which a ground or current cable issecured. The conductive material 1605, which can be copper, can be ineither a powder, granular, string or ribbon form. However, theconductive material should be distributed such that the an electricallyconductive path is formed from the surface 1600 to the ground point 125.The ground point 125 can be positioned anywhere on the substrate 1600.It is noted that in some exemplary embodiments it is not necessary forthe conductive material be distributed evenly throughout the entiresubstrate structure 1600 but it should be distributed sufficientlythroughout the workpiece surface 1610 to provide for a current path fromwhere a workpiece is positioned or started on the substrate surface1610. The matrix material 1603 can be any material, or combination ofmaterials which will not bond with the workpiece. The materials can benon-conductive and have a high melting temperature so that the surfaceof the matrix 1603 will not melt during the formation of the workpieceon the surface. As indicated above, the matrix material can be any oneof, or a combination of clay, ceramic. Other materials can include castiron, with a high carbon content or any other alloy which would becomebrittle when the additive process is conducted on the surface. Asdescribed above, the additive process has a relatively low (if any)admixture, so propagation of the alloy from the substrate into the buildwill be minimal. However, the propagation can be such that the firstlayer of the build becomes brittle, while at the same time still beingconductive. When the build is complete the user can then easily bend andbreak the brittle interface to separate the build from the substrate. Asindicated above, a ceramic material can be used for the substrate. Suchceramics should have a high melting temperature, such as Al₂O₃, or othersimilar ceramics. In another example, an aluminum material or alloy canbe used as a substrate for a mild steel build.

In a further exemplary embodiment, the substrate can be made from ametallic powder having a density such that the substrate provides thedesired conductivity and physical support for the build workpiece. Insuch embodiments, the powder can be easily knocked away from the buildpiece once completed. In even further exemplary embodiments, thesubstrate can be comprised of a conductive layer (e.g., copper, carbon,iron, etc.) placed on a base of nonconductive material, such as ceramic,which may or may not have conductive materials within the base material.By using a thin layer on a base material, the penetration into thesubstrate can be minimized, thus ensuring that there is no bonding tothe substrate.

As shown in FIG. 16, in some exemplary embodiments, the substrate 1600can have a contact zone 1620 in which the conductive material is presentand outside of which the conductive material is not present, or ispresent to a lesser extent so that the substrate 1600 is less ornon-conductive outside of the contact zone 1620. In such embodiments,the workpiece 110 is started or placed on the surface 1610 such that itcontacts the contact zone 1620 to ensure sufficient electrical contact,as outside of the contact zone 1620 little or no electrical conductivitywill exist. In such embodiments, the contact zone 1620 has an area whichis less than the area of the surface 1610. Further, the contact zone1620 can be shaped in any desired shape. Thus, in exemplary embodiments,to begin an additive manufacturing process the process begins in thecontact zone 1620 of the surface 1610 to ensure that a current path forthe workpiece exists. As the workpiece 110 is constructed portions ofthe workpiece can be formed on the surface 1610 outside of the contactzone 1620 so long as the workpiece is made as an integral piece—thushaving a constant current path. Thus, a current path will always beprovided for the manufacturing process, and the workpiece 110 can bemanufactured on a conductive surface 1610 which does not bond to theworkpiece 110, allowing for easy removal and processing of theworkpiece.

FIG. 17A depicts another exemplary embodiment where the substrate 1600has a lattice 1630 of conductive material which creates a grid structureon the surface 1610 of the substrate 100. The lattice 1630 is made froma conductive material, such as copper, is embedded in the material ofthe substrate 1600, which can be ceramic, clay or other non-conductivematerials. The lattice 1630 can be formed such that a grid structure isformed on the surface 1610 such that regardless of the size ororientation of the workpiece 110 to be formed, the workpiece willcontact at least some of the lattice 1630 to provide the neededconductive path. The lattice 1630 is to have a mesh size to provide thedesired spacing for the size of the workpieces that are to be made onthe substrate 1600. In some embodiments, the lattice 1630 can have adepth that goes through the substrate 1600, while in other embodimentsthe depth of the lattice 1630 does not go all the way through thesubstrate 1600. Further, the lattice structure 1630 is formed such thatthe structure is conductive throughout so that regardless of where aworkpiece makes contact with the lattice structure 1630 there is anelectrical path to the ground point 1625. Further, in exemplaryembodiments, the lattice structure 1630 can exist in the substrate 1600only in a contact zone similar to that described with respect to FIG.16. That is, the lattice structure exposed to the surface 1610 is onlyin a discrete area of the surface 1610 (i.e., contact zone) and thelattice is coupled to the ground point 1625. In such embodiments, solong as some portion of the workpiece is in the contact zone and makescontact with a portion of the lattice 1630, a current path exists toallow for the manufacture of the workpiece. Again, however, because mostof the surface 1610 is non-conductive and non-bonding, the removal andprocessing of the workpiece is easy as compared to known substrates.

FIG. 17B shows another exemplary embodiment of a substrate 1600 that canbe used with devices described herein. In this embodiment, the substrate1600 comprises a plurality of discrete ground points 1651/1652/1653,etc. distributed through an area of the substrate 1600. The points canbe distributed in a pattern, such as a lattice pattern such that theirrespective locations are known to the controller of any system using thesubstrate. The ground points are made from a conductive material, andcan be wires, pins, etc., and can pass through the substrate 1600 suchthat they each are also exposed on another surface of the substrate1600. In the embodiment shown in FIG. 17B the ground points pass throughthe substrate 1600 such that their other ends are exposed on the bottomsurface of the substrate 1600. In other embodiments, the other ends cancome out of a side face, if desired. Each of the ground points 1651,1652, 1653, etc. are electrically coupled to a switching circuit 1660which is also electrically coupled to the power supply of the system andto the controller, which controls the operation of ground switcheswithin the circuit 1660 as described below. Because the location of theground points are known, an additive process can be started on one ofthe ground points (e.g., point 1651) which serves as the initial groundpath for the additive process. Once the process is started, the puddlecan be moved along the surface 1610 until it reaches a next ground point1652. The switching circuit 1660 can allow the controller to switch theground point of the build process to the nearest ground point to theongoing additive process. That is, as the contact tip of the process ismoved the ground point can be switched to provide the nearest groundpath to the operation. Further, in other exemplary embodiments, theswitching circuit 1660 can open up more than one ground paths—through aplurality of ground points—to increase the amount of current that can beused for the process. Further, in exemplary embodiments, the switchingcircuit 1660 can be used to steer the ground current path to differentlocations to control the deposition process. For example, as the buildprocess nears an edge of the substrate 1600 the switch 1660 can switchto ground points which are closer to the center of the substrate 1660 toaid in controlling the deposition process and the puddle. This can alsobe used to aid in controlling the direction of an arc, to the extent anyarc is initiated in the deposition process.

FIG. 17C shows a further exemplary embodiment of the present invention,where the substrate 1600 further includes a conductor 1670 whichelectrically couples all of the ground points 1651, 1652, 1653, etc.,and the conductor 1670 is coupled to the power supply, to complete theground path for the deposition current. In such embodiments, noswitching circuit 1660 as described above need be used. In theembodiment shown, the conductor 1670 is a conductive plate or layermounted to a surface of the substrate 1600, to which all of the groundpoints are coupled. Of course, the conductor 1670 need not be on thebottom surface, but can also be on another surface of the substrate1600. During use, as the build structure contacts more than one groundpoint 1651, etc., additional ground paths are provided to the conductor1670, again allowing more current to be used in the process. In eitherof the above embodiments, the controller/power supply used for thedeposition process can control the deposition current level so as to notexceed an acceptable current level for any one ground point. That is, atthe beginning of a build process, if only one ground point 1651 is beingused, the current is controlled such that the current level does notexceed an acceptable level for a single ground point 1651. To do socould cause damage to the ground point. However, as the build proceedsto additional ground points, the controller can cause the current levelto rise because of the additional ground points contacted—because anincreased number of ground paths to the conductor 1670. Therefore, insuch embodiments, because the controller knows the location of each ofthe ground points, the controller can then increase the current asmultiple ground points are utilized. In such embodiments, the depositioncurrent can be increased incrementally with the contact of eachrespective ground point, or can be increased in a single step when asuitable number of ground points is contacted. For example, for adeposition current of 200 amps the controller can determined (usingstored information) that a minimum of 4 ground points are needed forsuch a current level. The controller/power supply can utilize a first,lower, current level (e.g., 50 amps) until at least 4 ground points arecontacted, at which time the deposition current is increased to theoptimal level. In other embodiments, the current can be increased inincrements as each new ground point is contacted until the minimumneeded ground points are contacted. For example, the current canincrease by 50 amps for each subsequent ground point, until the desireddeposition current level is reached. The current increase steps can bepredetermined/preprogrammed in the controller of the system.

In exemplary embodiments of the present invention, the ground points arewires or pins having an average diameter which is larger than that ofthe wire diameter used. In exemplary embodiments, the ground points arepins having an average diameter of at least 20% larger than the largestwire diameter used. In some exemplary embodiments, the diameter is inthe range of 20 to 80% larger than the diameter of the largest diameterwire. Further, as shown in FIG. 17C the pins can have a larger headarea—as shown—for additional contact with a workpiece. That is, the pinscan have a larger head area (e.g., like a nail, etc.) at the contactsurface of the substrate—see, e.g., FIG. 17C. To the extent the pins1651, etc. have a shape as shown in FIG. 17C, the larger head area isnot considered in determining the average diameter of the pin asdiscussed above.

In further exemplary embodiments, the ground points 1651, etc. (e.g.,pins, wires, rods, etc.) are removable and replaceable within thesubstrate 1600. For example, as shown in FIG. 17C, the pins simply restin holes in the substrate and act as the ground points described above.Through admixture the pins become secured to the workpiece as its built,and then upon completion the workpiece is removed, along with thesecured pins. Then, the pins/rods, etc. can be removed via a machiningprocess and new pins can be replaced in the substrate 1600 for the nextprocess. The removable pins 1651, etc. should be of a sufficient lengthso as to make contact with a workpiece being built on the substrate andthe contact plate 1670, so that a proper ground current path can bemade.

FIG. 18A depicts another exemplary embodiment of the present invention,where the substrate 1600 contains at least one cooling channel 1640through which a cooling medium can be passed during manufacture of aworkpiece, or at least during the initial manufacture of a workpiece.The cooling medium can be a gas or a liquid and is used to keep thesubstrate at a temperature such that no portion of the surface 1610melts, or is otherwise adhered, to a workpiece. By cooling the substrate1600 via the use of a cooling manifold/channel 1640, the surface 1610can be kept cool, and any electrically conductive materials on thesurface 1610 (e.g., lattice structure, conductive particles, etc.) canbe kept cool so that any layer of the workpiece formed on the surface1610 will not melt, or otherwise bond with the electrically conductivecomponents on the surface 1610. Other embodiments, can use other coolingmethods/processes without departing from the scope or spirit of thepresent invention. For example, passive heat pipes can be used.

Thus, in exemplary embodiments, a substrate is provided which providesthe needed electrically conductivity but also provides a non-bondingsurface such that the removal and processing of the workpiece aftermanufacturer is easier.

FIG. 18B depicts yet another structure that can be used with theexemplary additive manufacturing processes described herein. Theadditive manufacturing processes described herein can be used tomanufacture complex and delicate workpieces. The easy manufacture ofcomponents such as these can be aided by starting the manufacturingprocess from a non-horizontal traditional substrate or work surface. Forexample, it may be advantageous to manufacture the workpiece in ahanging configuration. That is, it may be easier to manufacture theworkpiece where the initial layers/deposition of the workpiece layersare hanging such that they extend from a bottom of a substrate—asopposed to a traditional bottom up, flat surface substrate. Theembodiment shown in FIG. 18B depicts an exemplary truss structure 1800which can be used in these situations. The truss structure 1800 can havea plurality of support components 1810 and 1820 which are electricallycoupled to each other—to allow for current flow. The truss structure1800 is configured such that a workpiece can be started at any point onthe structure 1800 as desired for a given workpiece. For example, if itis easier to manufacture a workpiece upside down, or from a top downprocess, the part can be started at a point on one of the members 1810and 820 and built downward by the processes described herein. Of course,the truss structure and the torch/contact tips being used should bedesigned such that the tips can be properly positioned in the trussstructure 1800. The part can then be built from the structure 1810/1820down to the surface of a substrate 1600 as needed. As shown the trussstructure 1800 can have its own ground contact point 1825, or can simplybe electrically conductive throughout. Further, in some exemplaryembodiments, the truss structure can have contact protrusions 1830 towhich the beginning of a part or workpiece is secured to start a buildoperation. These protrusions 1830 act as contact nodes to which thebeginning of a workpiece is started. These protrusions can make iteasier to begin a manufacturing process and can make it easier toseparate the final part from the truss structure—without damaging themanufactured part. The protrusions 1830 can be made integrally with theparts 1810/1820 of the structure 1800. In other embodiments, theprotrusions 1830 can be made of a different material and/or be easilyseparable from the structure. For example, the protrusions 1830 can bepins or other fastener type components having a head or protrusionportion to which a part can be secured and started for a manufacturingprocess. Upon completion the pins can be removed from the trussstructure allowing for easy removal of the manufactured part. The trussstructure 1800 can take any desired shape or configuration for a givenmanufacturing process.

In exemplary embodiments, the truss structure 1800 can be a metallicstructure that allows for the transfer of the current to the substrate1600—which can be any of the embodiments described above. In otherexemplary embodiments, the truss structure can be made of a non-bonding,but conductive material, as generally described above with respect toFIGS. 16 and 17. In any event, the structure 1800 should be constructedsuch that it can provide a current path to either the substrate 1600 ora ground point 1825 to allow for the proper flow of the heating current.

FIGS. 19A, 19B and 19C depict exemplary embodiments of an additivemanufacturing consumable 1900 that can be used with embodiments of theinvention described herein. It is generally understood that largediameter solid consumables require more current/energy to melt theconsumable. However, smaller diameter consumables require lesscurrent/energy to melt, such that a lesser amount of current/energy isneeded to melt a plurality of smaller diameter consumables that have,collectively, the same cross-sectional area as a single larger diametersolid wire. Thus, the consumable used in some exemplary embodiments ofthe present invention is a braided consumable 1900 made up from aplurality of wires 1903 which are braided. In some embodiments, thewires 1903 are the same, having the same diameter and composition.However, in other exemplary embodiments, the wires 1903 can be differentfrom each other. For example, in some embodiments, two different wiretypes can be used to make the braided consumable 1900. In such anembodiment, the wires can different based on diameter and/orcomposition. For example the center wire can have a first diameter andcomposition and the perimeter wires 1903 have a second diameter andcomposition, both of which are different than the first diameter andcomposition. This allows for the use of a consumable 1900 that hascustomized properties for a particular manufacturing process. It shouldbe noted that the methods and systems described herein to deposit solidor cored consumables can be used to deposit a braided consumable such asthat shown in FIG. 19A.

Further, in the embodiment shown in FIG. 19A, the center wire 1903′ is anon-braided wire, and the outer perimeter of wires 1903 are braidedaround the center wire 1903′. The braid can be made in a generallyhelical pattern along the length of the consumable 1900.

In some exemplary embodiments, the braiding of the consumable 1900 canbe used to increase the relative wire feed speed of a consumable type.For example, as shown in FIG. 19A the center consumable 1903 can be of afirst type/material, and the surrounding wires 1903 can be of adifferent type/material. Because the length of the surrounding (outside)wires is longer than the center wire, for a given length of theconsumable 1900 the effective deposition rates of each of the respectivewire types are different. The effective, relative deposition rate ofdifferent wires types can also be affected by the relative number ofwire types in a given bundle. Thus, embodiments of the present inventionallow for increased flexibility in the deposition chemistry.

FIGS. 19B and 19C depict another exemplary embodiment of a consumablethat can be used with embodiments of the present invention. However,unlike the consumable 1900 in FIG. 19A, the consumables 1900 in FIGS.19B and 19C have a void 1910 at the core of the consumable, where thecore 1910 is surrounded by a plurality of braided wires 1903. Thishollow consumable construction allows the consumable 1900 to be squeezedand “shaped” during deposition so as to allow the deposition process tobe customizable. This will be explained in more detail below.

The braiding of the wires 1903 which form the exterior of the consumable1900 is done in a general helical pattern, similar to known wirebraiding methodologies, but a void 1910 is maintained at the core of theconsumable 1900. Like in FIG. 19A, the wires 1903 can have the samediameter and composition in some embodiments, while in other embodimentsthe wires 1903 can have different properties. An example of this isdepicted in FIG. 19C, where the braiding includes a first wire type 1903having a first diameter and composition, and a second wire type 1905having a second diameter and composition. Of course, in someembodiments, even though the diameters of the wires 1903/1905 aredifferent, the compositions can be the same. As shown in FIG. 19C, thedifferent wires 1903/1905 alternate around the perimeter of thecross-section of the consumable 1900. In further exemplary embodiments,the wires 1903/1905 can have different melting temperatures which canprovide for customize deposition profiles and layering, as needed.

The void 1910 should be dimensioned such that the consumable 1900′remains relatively stable in the deposition process. If the void is toolarge, the consumable can become unstable and will not maintain itsintegrity in the deposition process. In exemplary embodiments, thediameter of the void 1910 is in the range of 5 to 40% of the effectivediameter of the consumable 1900′. The “diameter of the void” 1910 is thediameter of the largest circular cross-section that can be fit withinthe void 1910—as shown in FIG. 19C as the dashed circle. The “effectivediameter” of the consumable 1900′ is the diameter of a circle having thesame cross-sectional area of the combined cross-sectional area of all ofthe wires 1903/1905 that make up the consumable 1900′.

As indicated above, the consumable 1900 having a center void 1910 can beshaped during the deposition process to allow for changing of thedeposition characteristics of the consumable. This is generally depictedin FIGS. 20A and 20B, where the consumable 1900 has been squeezed in adirection relative to the travel direction of the consumable to achievethe desired width of the deposition. As described herein process andsystems of the present invention can be used to make complex shapes viaadditive manufacturing. Thus, workpieces and shapes having varyingthicknesses, etc. can be made. The consumable 1900 shown in FIGS. 19Band 19C allow these complex shapes and differing thicknesses to beeasily made due to the void. In FIG. 20A the consumable is squeezed in adirection normal to the travel direction which narrows the consumable1900 relative to the travel direction. By doing this, the resultantdeposition will be narrower than the original diameter of theconsumable. Similarly, FIG. 20B depicts the same consumable 1900 beingsqueezed in a direction along the travel direction, which results inwidening the consumable 1900 relative to the travel direction. As such,with such squeezing a wider deposit can be made as needed. As statedabove, the void 1910 should be of a size/diameter that allows for thedeformation of the consumable 1900 to change its relative width ascompared to its non-compressed state.

In some exemplary embodiments, the void 1910 can be filled with a fluxor powder of a desired chemistry that is needed for the deposition. Thiscan aid in delivering a desired material to the build that is not easilymade into wire, or transferable through the melting of the wire. Forexample, an abrasion resistant powder can be added as a flux.

FIG. 20C depicts another exemplary embodiment of a contact tip assembly2000 and consumable delivery system and method that can be used withembodiments of the present invention. In this embodiment, at least twoconsumables 2010 and 2020 are directed to the contact tip assembly 2000and the contact tip 2040, which has an orifice 2030 that allows bothconsumables to pass through. Unlike the above embodiments, theconsumables 2010 and 2020 are not braided. They can be delivered fromthe same consumable source (spool, reel, etc.) or can be delivered fromseparate sources. Further, they can be the same consumable, having thesame dimensions and composition, or can be different as desired for agiven manufacturing operation. In further exemplary embodiments, theconsumables 2010 and 2020 can be fed at different rates, and in someembodiments, the feed rates can be changed “on the fly” during adeposition process. Such embodiments, allow for the customization ofalloys for the build during the deposition process. For example, duringa first portion of the process the consumables 2010 and 2020 are fed atthe same rate, but at different stages of the build process theconsumable 2010 is slowed down or sped up as needed to create thedesired deposit chemistry.

Further, while two consumables are shown, other embodiments can usethree or more as needed. In the embodiment shown, the consumables 2010and 2020 are delivered to the orifice 2030 (which can be oval shaped, orany other shape to accommodate the consumables) and are then directed tothe workpiece as with known consumable delivery systems. Duringdeposition, the contact tip 2040 is oriented such that the consumablesprovide the desired deposition profile. Further, the contact tip 2040 isrotatable (as above described embodiments) to allow the consumables tobe oriented as designed and have the shape or profile of the depositionprocess to be changed as desired. For example, as shown, the orientationon the left shows an in-line orientation which will provide a narrowdeposit on the workpiece, but with an increased height as theconsumables are in-line in the travel direction. Then, as needed, thecontact tip 2040 can be rotated to the position shown on the right. Therotation can be effected by the controller 195 and motors, etc., and canbe used during changes in deposition direction, without the need tochange the orientation of the torch. The positioning on the right can beused when it is desired to increase the width of the deposit—in thetravel direction. It is also noted that in some embodiments, it may notbe necessary to feed both consumables 2010 and 2020 at the same time. Insuch embodiments, the consumables 2010 and 2020 would be fed by separatewire feeders (not shown) and the controller 195 can control which one ofthe consumables is being fed, or whether they are fed at the same time.In such embodiments, the consumable not being fed need not be withdrawnfrom the orifice 2030 and can thus be used to maintain the positioningof the consumable which is being fed. In such embodiments, the feedingof the consumables can be controlled by the controller 195—which willfeed either one, or both, of the of the consumables as needed at a givenmoment during the process.

Further, in the embodiment shown in FIG. 20C, each of the consumables2010 and 2020 are sharing the same current, as they are being directedthrough a single orifice 2030. In such embodiments, the current can comefrom a single power source, and the current is shared by eachconsumable. However, FIG. 20D depicts a different exemplary embodiment.In the embodiment shown in FIG. 20D the contact tip assembly 2000contains two electrically isolatable contact tip portions 2015 and 2025.The tip portions 2015 and 2025 deliver the consumables 2010 and 2020,respectively. However, the assembly 2000 contains a switching device ormechanism 2050 which can electrically couple the tip portions 2015 and2025 to each other such that they share a current, or can electricallyisolate the tip portions from each other. In an exemplary embodiment,each of the tip portions 2015 and 2025 are coupled to a separate powersupply (PS#1 and PS#2). When the switch 2050 is in an open position,each respective power supply can provide a separate and distinct heatingcurrent to the respective consumables. In such embodiments, theconsumables can be deposited at different rates, and or can be differentin size and composition. This can be controlled and used as similarembodiments described above using multiple consumables. However, in thisembodiment, as needed the controller 195 can close the switch, at whichtime the contact tip portions 2015 and 2025 become electrically coupledand can share a single current signal from one of the power suppliesP.S. #1 or P.S. #2. In such embodiments, it may only be needed to run asingle power supply for a given operation, to reduce power usage and oreliminate the need for synchronizing signals. In such embodiments, theswitch 2050 can be closed such that each of the tip portions 2015 and2025 can now be coupled to each other so that the consumables 2010 and2020 share the same signal from a single source. When the switch 2050 isopened the tip portions are electrically isolated from each other (via adielectric material or other appropriate means), and if both consumablesare to be deposited they would receive separate signals from separatepower supplies. Alternatively, at some point during a depositionoperation it may be only needed that a single consumable need bedeposited. Thus, only one power supply is operated, but the switch 2050is opened to isolated the other consumable for safety purposes. Theswitching mechanism 2050 can be any switch structure which is capable ofisolating and connecting the tip portions 2015 and 2025, and can beintegral to the tip assembly 2000, or can be remote from the assembly2000, as desired.

Turning now to FIGS. 21A and 21B, a diagrammatical view of arepresentative contact tip assembly 1950 is shown using the consumable1900 of FIG. 19B. FIGS. 21A and 21B show a view looking up at the exitportion of the contact tip assembly 1950, where FIG. 21A depicts theconsumable in a non-compressed state and FIG. 21B depicts the consumable1900 in a compressed state. It should be noted that the followingdescription of the contact tip assembly 1950 is intended to be exemplaryand those of skill in the art understand that other configurations anddesigns can be used to shape the consumable 1900 as desired to achievethe desired deposition during an additive manufacturing process.

As shown, the contact tip assembly 1950 has a consumable opening 1951through which the consumable passes. While the opening 1951 is shown assquare, embodiments of the present invention are not limited in thisregard and other shapes can be used so long as the consumable 1900 canpass through in both its compressed and non-compressed state. In theembodiment shown, the assembly 1950 has two pairs of contact plungers1953 and 1955. The plungers are movable relative to the opening 1951, asshown, such that they can extend into the opening and thus apply acompression force on the consumable 1900. The contact plungers 1953 and1955 are oriented such that one pair of plungers 1953 are moveable in adirection normal to the direction of movement of the other set ofplungers 1955. Thus, as shown in FIG. 21B the plungers 1953/1955 cansqueeze the consumable 1900 in a desired direction to attain the desiredshape. Each set of plungers can be moved via known actuation devices1956, such as linear actuators, etc. and can be controlled by thecontroller 195 (not shown in these figures). Further, each of theplungers 1953/1955 are configured to provide the heating currentwaveform to the consumable 1900 such that the heating current isdelivered to the consumable 1900 via the plungers. It is noted thatalthough one actuator 1956 and bias 1957 are shown in the Figures,exemplary embodiments would have similar components for each of theplungers.

As shown in FIG. 21A, during a non-compressed state, each of theplungers 1953/1955 make contact with the consumable 1900 to deliver theheating current. The plungers 1953/1955 are held at a position, relativeto the opening 1951, to ensure that consumable 1900 is maintain in itsnatural state. Then, during deposition, it is determined (for example,by the controller) that a width of the consumable should be changed toachieve a desired deposition configuration—either the consumable shouldbe made wider or narrower, as needed. Based on this information, thecontroller 195 causes the plungers 1955 to be actuated (via actuators1956) and moved inward to compress the consumable 1900 as shown in FIG.21B. Additionally, to accommodate the change in shape of the consumable1900 the plungers 1953 are withdrawn to allow the shape of theconsumable to change. However, in exemplary embodiments, the withdrawnplungers 1953 still make contact with the consumable 1900 to hold theconsumable 1900 at the proper position and to deliver the heatingcurrent.

During the deposition process, the shape of the consumable 1900 can bechanged “on the fly” by moving the plungers to achieve the desiredshape. For example, the controller 195 can control the plungers1953/1955 to retract and extend as needed during the deposition tochange the shape of the consumable 1900 to go from a wide deposition toa narrow deposition and back again, without stopping the depositionprocess.

As stated above, the movement/actuation of the plungers 1953/1955 can beeffected by any known actuators, movement devices to effect the desiredmotion. In some exemplary embodiments, (not shown here) each plunger inthe respective pair of plungers can be mechanical linked to each othersuch that their relative motions are maintained consistent with eachother. In such embodiments, rather than having a separate actuator foreach plunger, a single actuator can be used for each respective pair,and because of a mechanical linkage each of the plungers will moveappropriately.

Further, as indicated above, the controller 195 can control theactuation of the plungers based on a desired shape to be constructed. Infurther exemplary embodiments, the assembly 1950 can be rotated asdesired during the deposition operation to achieve a desired shape. Thatis, the assembly 1950 can be coupled to a rotation motor and/or roboticarm (or other similar motion device) and the controller 195 (or othersystem controller) can cause the assembly to rotate as needed, and haveany of the plungers activated to achieve the desired consumable, andthus deposition, shape.

FIG. 22 depicts another exemplary embodiment of a consumable 2000 thatcan be used with exemplary embodiments of the present invention. Theconsumable 2000 includes a similar braided structure of wires 2003 witha space 2010 as described above, but also includes a sheath 2015. Thesheath 2015 can be constructed and formed similar to known sheathstructures used for welding or brazing consumables. As shown, in thisembodiment, the sheath 2015 complete encloses the wires 2003 and has aseam 2017, which is a butt seam. The sheath 2015 can be made of anymaterial desired to deposited on the work piece. In some embodiments thesheath 2015 can be the same material as the wires 2003, while in otherembodiments the sheath can be made of a different material/have adifferent composition. The sheath 2015 can also aid in the consumable2000 maintaining its shape after it is reformed by the plungers in thecontact tip assembly of FIGS. 21A and 21B. Specifically, the squeezingof the wire through the orifice 1951 will cause the sheath 2015 toplastically deform, thus causing the consumable 2000 to hold the desiredshape more easily. This can allow for the stick out of the consumable2000 to be increased during a deposition process.

FIG. 23 depicts another exemplary consumable 2100 that can be used withembodiments of the present invention. The consumable 2100 contains asheath 2110 and a core 2120, where the sheath 2110 has a lower meltingtemperature than the core 2120. By having such a divergent meltingtemperature, embodiments of the consumable 2100 can provide increasedcontrol over the manufacturing of a component. In embodiments where theconsumable melts at the generally same temperature throughout, thedynamics of the molten puddle created play an important role in thedeposition and build process. In certain instances the controlling ofthe puddle can be difficult, particularly in high precisionmanufacturing processes, or where the thickness of the workpiece beingconstructed is very thin. In such applications the puddle dynamics canbe hard to control and account for. However, when using the consumable2100 the sheath 2110 melts prior to the core 2120. The molten sheathmaterial then provides a molten matrix to adhere the core material tothe workpiece. In such applications the importance of the puddle isdecreased and in some instances, the puddle can be eliminated. Further,in alternative embodiments, the size and/or depth of the puddle can bereduced as the puddle and molten sheath material will work together toadhere the core material to the workpiece. As such, the dynamics of thepuddle can be less important when using the consumable 2100.

In exemplary embodiments the core 2120 can be a solid core, while inother embodiments the core 2120 can be powder or particles of a desiredmaterial. In such embodiments, the consumable 2100 can be shaped (asdiscussed above) to achieve a desired deposition. That is, because thecore 2120 can be powder or granular, the exterior of the consumable 2100can be shaped and squeezed to achieve a desired consumable profile. Inadditional embodiments the consumable can be constructed like that shownin at least FIG. 22, where the sheath surrounds a plurality ofindividual wires, and where at least some (or all) of the wires 2003have a melting temperature which is higher than the sheath 2015. Infact, in some of such embodiments, the wires 2003 can have differentmelting temperatures relative to each other. For example, a first numberof the wires 2003 can have a first melting temperature (higher than thesheath melting temperature) and a second number of the wires 2003 canhave a melting temperature which is either higher or lower than themelting temperature of the first number of wires 2003. Such embodimentscan provide increased flexibility in the melt and build profile of theconsumable. Further, in some embodiments the heat source (e.g. laser)and/or current are controlled such that at least some of the core 2120is also melted during the deposition process. However, in otherembodiments, the material of the core 2120 is not melted during thedeposition process. That is, the sheath 2110 is melted, and the liquidsheath material is used to secure the unmelted core material to theworkpiece. In such embodiments, the workpiece is created in layers,alternating between the molten sheath material and the core material. Itis noted that although FIG. 23 depicts the consumable 2100 as having acircular cross-section, embodiments of the present invention are notlimited in this regard. The consumable 2100 can also have any desiredshape which benefits the construction of the workpiece as desired. Forexample, the consumable 2100 can have a square, rectangular, polygonal,or elliptical cross-section. Of course, other shape s can be used aswell.

In exemplary embodiments, the materials of the sheath 2110 and the core2120 are selected such that the sheath 2110 melts at a temperature whichis in the range of 5 to 45% lower than that of the core material. Infurther exemplary embodiments, the melting temperature of the sheath2110 is in the range of 10 to 35% lower than that of the core material.Of course, the exact composition of the materials for each of the sheathand the core are to be selected based on the desired composition andconstruction of the workpiece being built.

FIG. 24A depicts another exemplary embodiment, where the consumable 2200has a non-circular cross-section and the sheath material 2210 does notextend around the entire perimeter of the consumable 2200. That is, theconsumable 2200 has an asymmetric cross-section. For example, in theembodiment shown the sheath material 2210 is only position on one sideof the core material 2220 of the consumable. FIG. 24B depicts anothersuch exemplary embodiment, where the overall shape of the consumable isan hexagon and the sheath material 2210′ covers only 5 sides of thehexagonal cross-section of the core 2220′. Of course, other shapes andcoverages can be used based on the desired performance and depositionproperties of the consumable. FIG. 24C is another exemplary embodiment,which shows a consumable 2200″ having a symmetric cross-section, but thedistribution of the sheath material 2210″ and the core material 2220″ isnot symmetrical. This configuration allows the consumable to be usedwith contact tips and equipment designed for typical symmetricconsumables, but the consumable itself is asymmetric. In suchembodiments, the sheath material 2210 melts and provides adhesion forthe core portion 2220 of the consumable, but does not melt from allaround the consumable. In such embodiments, the consumable can beoriented as desired prior to adhesion during the deposition process. Thesheath material acts as an adhesion material which binds or bonds thecore material to the workpiece. Further, in such embodiments, thecurrent/heat input is controlled to ensure the desired melting of thesheath material is attained without fully melting the core material.

FIG. 24D is a further exemplary embodiment of a consumable 2200′″ thatcan be used with embodiments of the present invention. The consumable2200′″ is similar to those discussed above, except that the sheath layer2210′″ has a layered construction. In such embodiments, the sheath layer2210′″ can be either a solid material or can be a flux. In fact, in anyof the embodiments, discussed above, the sheath layer can be a flux, andnot be a solid metallic sheath. In those embodiments, in someapplications, it may be desirable to place a material within the fluxsheath that should not be melted during the deposition process (or themelting is to be minimized). To achieve this, some embodiments use alayered sheath/flux 2210′″ where the composition of the flux against thesurface S of the core 2220′″ is different than the chemistry of the fluxat the outer edge of the flux. This is shown in FIG. 24D as layers A andB, where layer A has a first composition and layer B has a secondcomposition. The creation of these layers can use known depositiontechniques, which need not be discussed herein. This type ofconstruction allows materials in the layer B to be removed from directheat in the core 2220′″ which would otherwise melt components in thelayer B. For example, it may be desirable to deposit tungsten carbide inthe puddle, which could be susceptible to melting if they were in directcontact with the core 2220′″. In this embodiment, the layer A acts as aheat buffer, allowing the materials of layer B to be deposited withlittle or no melting. Of course, it should be understood that thedelineation between the two layers A and B need not be a clear, preciseline, but can be a transition from one composition to another. Further,the shape and relative cross-sectional area of the layer B, relative tothe layer A, can be determined based on the desired composition of theapplication. FIG. 24D is shown as an exemplary embodiment and othershapes and configurations can be used without departing from the spiritor scope of the present invention.

A user interface coupled to a computer illustrates one possible hardwareconfiguration to support the systems and methods described herein,including the controller 195, or similar system used to control and/oroperate the systems described herein. In order to provide additionalcontext for various aspects of the present invention, the followingdiscussion is intended to provide a brief, general description of asuitable computing environment in which the various aspects of thepresent invention may be implemented. Those skilled in the art willrecognize that the invention also may be implemented in combination withother program modules and/or as a combination of hardware and software.Generally, program modules include routines, programs, components, datastructures, etc., that perform particular tasks or implement particularabstract data types.

Moreover, those skilled in the art will appreciate that the inventivemethods may be practiced with other computer system configurations,including single-processor or multiprocessor computer systems,minicomputers, mainframe computers, as well as personal computers,hand-held computing devices, microprocessor-based or programmableconsumer electronics, and the like, each of which may be operativelycoupled to one or more associated devices. The illustrated aspects ofthe invention may also be practiced in distributed computingenvironments where certain tasks are performed by remote processingdevices that are linked through a communications network. In adistributed computing environment, program modules may be located inboth local and remote memory storage devices.

The controller 195 can utilize an exemplary environment for implementingvarious aspects of the invention including a computer, wherein thecomputer includes a processing unit, a system memory and a system bus.The system bus couples system components including, but not limited tothe system memory to the processing unit. The processing unit may be anyof various commercially available processors. Dual microprocessors andother multi-processor architectures also can be employed as theprocessing unit.

The system bus can be any of several types of bus structure including amemory bus or memory controller, a peripheral bus and a local bus usingany of a variety of commercially available bus architectures. The systemmemory can include read only memory (ROM) and random access memory(RAM). A basic input/output system (BIOS), containing the basic routinesthat help to transfer information between elements within the computer,such as during start-up, is stored in the ROM.

The controller 195 can further include a hard disk drive, a magneticdisk drive, e.g., to read from or write to a removable disk, and anoptical disk drive, e.g., for reading a CD-ROM disk or to read from orwrite to other optical media. The controller 195 can include at leastsome form of computer readable media. Computer readable media can be anyavailable media that can be accessed by the computer. By way of example,and not limitation, computer readable media may comprise computerstorage media and communication media. Computer storage media includesvolatile and nonvolatile, removable and non-removable media implementedin any method or technology for storage of information such as computerreadable instructions, data structures, program modules or other data.Computer storage media includes, but is not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (DVD) or other magnetic storage devices, or any othermedium which can be used to store the desired information and which canbe accessed by a user interface coupled to the controller 195.

Communication media typically embodies computer readable instructions,data structures, program modules or other data in a modulated datasignal such as a carrier wave or other transport mechanism and includesany information delivery media. The term “modulated data signal” means asignal that has one or more of its characteristics set or changed insuch a manner as to encode information in the signal. By way of example,and not limitation, communication media includes wired media such as awired network or direct-wired connection, and wireless media such asacoustic, RF, infrared and other wireless media. Combinations of any ofthe above should also be included within the scope of computer readablemedia.

A number of program modules may be stored in the drives and RAM,including an operating system, one or more application programs, otherprogram modules, and program data. The operating system in the computeror the user interface 300 can be any of a number of commerciallyavailable operating systems.

In addition, a user may enter commands and information into the computerthrough a keyboard and a pointing device, such as a mouse. Other inputdevices may include a microphone, an IR remote control, a track ball, apen input device, a joystick, a game pad, a digitizing tablet, asatellite dish, a scanner, or the like. These and other input devicesare often connected to the processing unit through a serial portinterface that is coupled to the system bus, but may be connected byother interfaces, such as a parallel port, a game port, a universalserial bus (“USB”), an IR interface, and/or various wirelesstechnologies. A monitor or other type of display device, may also beconnected to the system bus via an interface, such as a video adapter.Visual output may also be accomplished through a remote display networkprotocol such as Remote Desktop Protocol, VNC, X-Window System, etc. Inaddition to visual output, a computer typically includes otherperipheral output devices, such as speakers, printers, etc.

A display can be employed with a user interface coupled to thecontroller 195 to present data that is electronically received from theprocessing unit. For example, the display can be an LCD, plasma, CRT,etc. monitor that presents data electronically. Alternatively or inaddition, the display can present received data in a hard copy formatsuch as a printer, facsimile, plotter etc. The display can present datain any color and can receive data from a user interface via any wirelessor hard wire protocol and/or standard.

The computer can operate in a networked environment using logical and/orphysical connections to one or more remote computers, such as a remotecomputer(s). The remote computer(s) can be a workstation, a servercomputer, a router, a personal computer, microprocessor basedentertainment appliance, a peer device or other common network node, andtypically includes many or all of the elements described relative to thecomputer. The logical connections depicted include a local area network(LAN) and a wide area network (WAN). Such networking environments arecommonplace in offices, enterprise-wide computer networks, intranets andthe Internet.

When used in a LAN networking environment, the computer is connected tothe local network through a network interface or adapter. When used in aWAN networking environment, the computer typically includes a modem, oris connected to a communications server on the LAN, or has other meansfor establishing communications over the WAN, such as the Internet. In anetworked environment, program modules depicted relative to thecomputer, or portions thereof, may be stored in the remote memorystorage device. It will be appreciated that network connectionsdescribed herein are exemplary and other means of establishing acommunications link between the computers may be used.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the invention without departing from its scope.Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed, but that the invention will includeall embodiments falling within the scope of the appended claims.

We claim:
 1. An additive manufacturing system, comprising: a high energydevice which irradiates a surface of a workpiece with a high energydischarge to create first and second molten puddles on a surface of saidworkpiece; a first power supply which supplies a first heating signal toa first wire where said first heating signal comprises a plurality offirst current pulses and where each of said first current pulses of saidfirst heating signal creates a molten droplet on a distal end of saidfirst wire which is deposited into said first puddle; and a second powersupply which supplies a second heating signal to a second wire wheresaid second heating signal comprises a plurality of second currentpulses and where each of said second current pulses of said secondheating signal creates a molten droplet on a distal end of said secondwire which is deposited into said second puddle; and wherein each ofsaid first current pulses reaches a peak current level after a distalend of said wire contacts said first puddle, wherein said first heatingsignal has no current in between said plurality of said first currentpulses; wherein said distal end of said first wire is not in contactwith said first puddle between subsequent peak current levels of saidfirst current pulses; wherein said first power supply controls saidfirst heating current such that no arc is created between said firstwire and said work piece during said first current pulses; and whereinsaid first and second molten puddles are distinct molten puddles.
 2. Thesystem of claim 1, wherein each of the distinct molten puddles areadjacent to each other on the workpiece.
 3. The system of claim 1,wherein said first and second wires are positioned in line in a traveldirection and wherein said second wire trails said first wire and saidsecond wire is positioned such that it is deposited onto a layer createdby said first wire.
 4. The system of claim 1, wherein said first wirehas a different composition than said second wire.
 5. The system ofclaim 1, wherein said first wire has a first wire feed speed and saidsecond wire has a second wire feed speed which is different than saidfirst wire feed speed.
 6. The system of claim 1, further comprising afirst contact tip for said first wire and a second contact tip for saidsecond wire, where said first and second contact tips deliver said firstand second heating signals, respectively, to said first and secondwires, and wherein said first and second contact tips are movablerelative to each other.
 7. The system of claim 1, further comprising afirst contact tip for said first wire and a second contact tip for saidsecond wire, where said first and second contact tips deliver said firstand second heating signals, respectively, to said first and secondwires, and wherein said first wire has a first stick out distance whichis a different from a second stick out distance for said second wire. 8.The system of claim 1, further comprising a first contact tip for saidfirst wire and a second contact tip for said second wire, where saidfirst and second contact tips deliver said first and second heatingsignals, respectively, to said first and second wires, and a contact tipassembly which couples said first and second contact tips to each other,wherein said contact tip assembly is rotatable relative to a traveldirection of said first and second wires.
 9. The system of claim 1,wherein said first power supply monitors a voltage of said first heatingsignal when said first wire is in contact with said first puddle andcompares said voltage to an arc detection voltage level.
 10. An methodof additive manufacturing, comprising: irradiating a surface of aworkpiece with a high energy discharge to create first and second moltenpuddles on a surface of said workpiece; supplying a first heating signalto a first wire where said first heating signal comprises a plurality offirst current pulses and where each of said first current pulses of saidfirst heating signal creates a molten droplet on a distal end of saidfirst wire which is deposited into said first puddle; and supplying asecond heating signal to a second wire where said second heating signalcomprises a plurality of second current pulses and where each of saidsecond current pulses of said second heating signal creates a moltendroplet on a distal end of said second wire which is deposited into saidsecond puddle; and wherein each of said first current pulses reaches apeak current level after a distal end of said wire contacts said firstpuddle, wherein said first heating signal has no current in between saidplurality of said first current pulses; wherein said distal end of saidfirst wire is not in contact with said first puddle between subsequentpeak current levels of said first current pulses; wherein said firstheating current is controlled such that no arc is created between saidfirst wire and said workpiece during said first current pulses; andwherein said first and second molten puddles are distinct moltenpuddles.
 11. The method of claim 10, wherein each of the distinct moltenpuddles are adjacent to each other on the workpiece.
 12. The method ofclaim 10, wherein said first and second wires are positioned in line ina travel direction and wherein said second wire trails said first wireand said second wire is positioned such that it is deposited onto alayer created by said first wire.
 13. The method of claim 10, whereinsaid first wire has a different composition than said second wire. 14.The method of claim 10, wherein said first wire is fed at a first wirefeed speed and said second wire is fed at a second wire feed speed whichis different than said first wire feed speed.
 15. The method of claim10, further comprising passing said first wire through a first contacttip and passing said second wire through a second contact tip, wheresaid first and second contact tips deliver said first and second heatingsignals, respectively, to said first and second wires, and moving saidfirst and second contact tips relative to each other.
 16. The method ofclaim 10, further comprising passing said first wire through a firstcontact tip and passing said second wire through a second contact tip,where said first and second contact tips deliver said first and secondheating signals, respectively, to said first and second wires, andwherein said first wire is maintained at a first stick out distancewhich is a different from a second stick out distance for said secondwire.
 17. The method of claim 10, further comprising passing said firstwire through a first contact tip and passing said second wire through asecond contact tip, where said first and second contact tips deliversaid first and second heating signals, respectively, to said first andsecond wires, and rotating said second contact tip relative to saidfirst contact tip during said additive manufacturing.
 18. The method ofclaim 10, further comprising monitoring a voltage of said first heatingsignal when said first wire is in contact with said first puddle andcomparing said voltage to an arc detection voltage level.